Why You’ll Love This Recipe:
These Ultimate Butter Tart Squares capture all the beloved flavors of traditional Canadian butter tarts in an easy-to-make bar form that’s perfect for feeding a crowd. Instead of making individual tart shells, this recipe transforms the classic dessert into shareable squares that are much simpler to prepare while delivering that same irresistible combination of buttery shortbread crust and gooey, caramelized filling.
What makes this recipe truly special is its foolproof nature and incredible versatility. The shortbread crust provides the perfect buttery foundation, while the filling strikes that ideal balance between sweet and slightly tangy that butter tart lovers crave. Whether you’re preparing for a bake sale, family gathering, or holiday celebration, these Ultimate Butter Tart Squares are guaranteed crowd-pleasers that require minimal fuss but deliver maximum satisfaction.
The recipe is wonderfully forgiving, making it perfect for both novice and experienced bakers. You can customize the filling with raisins for traditionalists or leave them plain for those who prefer a cleaner flavor profile. Best of all, these squares actually improve in flavor after sitting overnight, making them an excellent make-ahead dessert option.
Ingredients You’ll Need:

Crust:
- 2 cups of all-purpose flour (this is regular baking flour) – Forms the base of your buttery shortbread crust
- 4 tablespoons of icing sugar (powdered sugar) – Adds sweetness and creates a tender texture
- 1 cup of cold, unsalted butter (cut into small cubes) – Essential for flaky, buttery crust
- 1–2 tablespoons of cold water (optional, only if the crust is too dry) – Use sparingly if needed
Filling:
- ½ cup of unsalted butter – Creates the rich, gooey texture that makes butter tarts irresistible
- 3 cups of brown sugar (lightly packed into the measuring cup) – The heart of the caramelized filling
- 4 large eggs – Provides structure and richness to the filling
- 1–2 tablespoons of white vinegar – The secret ingredient that adds subtle tang and prevents crystallization
- 1 tablespoon of vanilla extract – Enhances the overall flavor profile
- Optional: ¾ cup of raisins – Classic addition for traditional butter tart flavor
How to Make Butter Tart Squares:
Step-by-Step Instructions:
Step 1: Prepare Your Pan and Oven Preheat your oven to 350°F (175°C). Line a 9×13-inch baking pan with parchment paper, leaving some overhang for easy removal. Lightly grease the parchment paper to ensure your Ultimate Butter Tart Squares won’t stick.
Step 2: Make the Shortbread Crust In a large mixing bowl, combine the all-purpose flour and icing sugar. Add the cold, cubed butter and use a pastry cutter or your fingertips to work the butter into the flour mixture until it resembles coarse crumbs with some pea-sized butter pieces remaining. The mixture should hold together when squeezed but still look slightly crumbly.
Step 3: Check Crust Consistency Press a handful of the mixture together in your palm. If it holds together nicely, you’re ready to proceed. If it seems too dry and won’t hold together, add 1 tablespoon of cold water and mix gently. Add the second tablespoon only if absolutely necessary.
Step 4: Press the Crust Transfer the crust mixture to your prepared pan and press it evenly into the bottom using your hands or the bottom of a measuring cup. Make sure the crust extends slightly up the sides and is evenly distributed with no thin spots.
Step 5: Pre-bake the Crust Bake the crust for 15-18 minutes, or until it’s lightly golden around the edges and set. Remove from the oven and set aside while you prepare the filling. Keep the oven at 350°F.
Step 6: Prepare the Filling In a medium saucepan, melt the ½ cup of butter over medium heat. Remove from heat and whisk in the brown sugar until well combined. The mixture will be thick and slightly grainy at this point, which is normal.
Step 7: Add Wet Ingredients Allow the butter and sugar mixture to cool for 2-3 minutes, then whisk in the eggs one at a time, ensuring each is fully incorporated before adding the next. Stir in the vanilla extract and white vinegar. The vinegar might seem unusual, but it’s the secret to authentic butter tart flavor.
Step 8: Add Optional Ingredients If using raisins, fold them into the filling mixture now. Make sure they’re evenly distributed throughout the filling.
Step 9: Assemble and Bake Pour the filling over the pre-baked crust, spreading it evenly with a spatula. The filling should reach almost to the top of the crust edges. Bake for 25-30 minutes, or until the filling is set around the edges but still slightly jiggly in the center.
Step 10: Cool Completely Remove from the oven and allow the Ultimate Butter Tart Squares to cool completely in the pan, at least 2 hours. For best results, refrigerate for 1 hour before cutting to ensure clean cuts.
Step 11: Cut and Serve Using the parchment paper overhang, lift the entire dessert from the pan. Cut into squares using a sharp knife, wiping the blade clean between cuts for the neatest presentation.
Helpful Tips:
Keep Butter Cold: Cold butter is crucial for a proper shortbread crust. If your kitchen is warm, chill the flour mixture and butter cubes in the refrigerator for 15 minutes before mixing.
Don’t Overwork the Crust: Mix the crust just until it comes together. Overworking will result in a tough, dense base rather than the tender shortbread texture you want.
Test for Doneness: The filling should be set around the edges but still have a slight jiggle in the center when done. It will continue to set as it cools.
The Vinegar Secret: Don’t skip the vinegar! It’s what gives these Ultimate Butter Tart Squares their authentic butter tart flavor and helps prevent the brown sugar from crystallizing.
Make Ahead Magic: These squares taste even better the next day as the flavors meld together. They’re perfect for advance preparation.
Details:
Prep Time: 20 minutes
Bake Time: 45 minutes (15 minutes crust + 30 minutes assembled)
Cooling Time: 2 hours
Total Time: 3 hours 5 minutes
Servings: 24 squares
Difficulty: Easy to Moderate
Category: Dessert/Bars
Cuisine: Canadian
Calories: Approximately 285 per square
Notes:

These Ultimate Butter Tart Squares are incredibly versatile and can be customized to suit different preferences. For a more indulgent version, try adding chopped pecans or walnuts along with or instead of the raisins. Some bakers enjoy adding a pinch of salt to the filling to enhance the sweet-salty contrast.
The squares can be made gluten-free by substituting the all-purpose flour with a quality gluten-free flour blend, though the texture may be slightly different. For those watching their sugar intake, you can reduce the brown sugar by up to ½ cup, though this will affect the characteristic gooey texture.
Storage is simple and these squares actually improve with time. The filling becomes more cohesive and the flavors deepen, making them an excellent choice for holiday baking or any time you need to prepare desserts in advance.
Frequently Asked Questions:
Q: Why do my butter tart squares have a soggy bottom? A: This usually happens if the crust wasn’t pre-baked long enough or if the filling was too hot when poured over the crust. Make sure the crust is lightly golden before adding the filling, and let the filling cool for a few minutes after cooking.
Q: Can I make these Ultimate Butter Tart Squares without raisins? A: Absolutely! The raisins are completely optional. You can leave them out for a cleaner flavor, or substitute with chopped nuts, chocolate chips, or dried cranberries.
Q: How do I know when the filling is properly set? A: The edges should be firm and set, while the center should have just a slight jiggle when you gently shake the pan. The filling will continue to set as it cools.
Q: Can I double this recipe? A: Yes, but you’ll need to use two 9×13-inch pans or one very large sheet pan. Don’t try to make them thicker in a single pan as the cooking times will be off.
Q: What’s the purpose of the vinegar in butter tarts? A: The vinegar is traditional in Canadian butter tarts. It adds a subtle tang that balances the sweetness and helps prevent the brown sugar from crystallizing, ensuring a smooth filling.
Storage Instructions:
Store your Ultimate Butter Tart Squares covered at room temperature for up to 1 week. They actually taste better after the first day as the flavors meld together and the texture becomes more cohesive.
For longer storage, these squares freeze beautifully for up to 3 months. Wrap individual squares in plastic wrap and store in a freezer-safe container. Thaw at room temperature for about 30 minutes before serving.
If you live in a very humid climate, you may want to store them in the refrigerator to prevent the filling from becoming too soft. Let them come to room temperature before serving for the best texture and flavor.
Related Recipes:
For more delicious Canadian-inspired treats and bar recipes, check out these favorites from Run of Life:
- Classic Canadian Nanaimo Bars
- Traditional Butter Tarts
- Maple Walnut Fudge Squares
- Shortbread Cookie Bars
- Caramel Pecan Squares
Conclusion:
These Ultimate Butter Tart Squares successfully capture the essence of Canada’s beloved butter tarts in a convenient, shareable format that’s perfect for any occasion. The combination of buttery shortbread crust and gooey, caramelized filling creates a dessert that’s both nostalgic and irresistibly delicious.
What makes this recipe truly special is its accessibility and reliability. Unlike traditional butter tarts that require individual pastry shells and careful timing, these squares simplify the process while delivering all the flavors that make butter tarts so cherished. The addition of vinegar might seem unusual, but it’s this authentic touch that elevates these squares from good to absolutely exceptional.
Whether you’re introducing someone to the wonderful world of butter tarts or satisfying your own craving for this Canadian classic, these Ultimate Butter Tart Squares are sure to become a treasured recipe in your collection. They represent the perfect balance of tradition and convenience, proving that sometimes the best desserts are the ones that bring people together around simple, honest flavors. Make a batch today and experience why butter tarts have captured hearts across Canada and beyond!