Homemade Lemon Crumb Bars
These Homemade Lemon Crumb Bars are a delightful fusion of tangy lemon curd and a buttery, crumbly oat crust. Each bite offers a harmonious balance of zesty brightness and comforting sweetness, making them an irresistible treat for any occasion. Perfect for picnics, dessert tables, or simply a sunny afternoon indulgence, these bars are sure to become a cherished favorite.
Prep Time
20 minutes
Cook Time
28 minutes
Total Time
3 hours (including cooling time)
Servings
16 squares
Keywords
Why This Recipe Delivers
- Bursting with bright, zesty lemon flavor that invigorates the palate.
- Features a perfectly balanced texture: a tender, crumbly oat crust complemented by a creamy, smooth lemon filling.
- Surprisingly simple to make, requiring basic ingredients and straightforward steps.
- Ideal for make-ahead convenience, as they improve with a little chill time.
- A crowd-pleasing dessert that appeals to both lemon lovers and those who enjoy a comforting sweet treat.
Ingredients
- 125 grams (1 cup) all-purpose flour
- 90 grams (1 cup) old-fashioned oats
- 1.25 grams (1/4 teaspoon) salt
- 3.75 grams (3/4 teaspoon) baking soda
- 140 grams (10 tablespoons) unsalted butter, melted
- 100 grams (1/2 cup) light brown sugar, packed
- 10 ml (2 teaspoons) pure vanilla extract, divided
- 1 (396 grams or 14 oz) can sweetened condensed milk
- 30 ml (2 tablespoons) sour cream (or plain yogurt)
- 1 large egg yolk
- 60 ml (1/4 cup) freshly squeezed lemon juice
- 1 tablespoon finely grated lemon zest (from 2-3 medium lemons)
Instructions
- Prepare your baking pan by preheating your oven to 175°C (350°F). Line an 8×8-inch (20×20 cm) baking pan with parchment paper, ensuring it overhangs on the sides to create a sling for easy removal, then lightly spray the parchment with nonstick spray.
- In a medium-sized bowl, thoroughly whisk together the all-purpose flour, old-fashioned oats, salt, and baking soda. This ensures an even distribution of the dry ingredients.
- In a separate larger bowl, combine the melted unsalted butter, packed light brown sugar, and 5 ml (1 teaspoon) of the pure vanilla extract. Whisk until the mixture is smooth and well combined.
- Gradually add the dry ingredient mixture to the wet butter mixture. Mix with a spoon or spatula until just combined and a crumbly dough forms. Be careful not to overmix, as this can lead to a tough crust.
- Reserve approximately 180 grams (3/4 cup) of this crumb mixture to use as a topping later. Press the remaining crumb mixture evenly into the bottom of your prepared 8×8-inch baking pan. Use the bottom of a flat glass or your fingers to create a firm, compact crust.
- Place the pan with the pressed crust into the preheated oven and bake for exactly 10 minutes. This pre-baking step helps to create a sturdy foundation for the lemon filling.
- While the crust is baking, prepare the luscious lemon filling. In a medium bowl, whisk together the sweetened condensed milk, sour cream (or plain yogurt), large egg yolk, freshly squeezed lemon juice, finely grated lemon zest, and the remaining 5 ml (1 teaspoon) of pure vanilla extract until the mixture is completely smooth and uniform.
- Once the crust has finished its initial bake, carefully remove the pan from the oven. Pour the prepared lemon filling evenly over the warm, par-baked crust. The heat from the crust will begin to gently set the edges of the filling.
- Evenly sprinkle the reserved crumb topping over the lemon filling. Return the pan to the oven and continue to bake for another 17 to 20 minutes, or until the crumb topping is beautifully golden brown and the lemon filling appears set, with only a slight jiggle in the very center.
- Once baked, remove the pan from the oven and place it on a wire rack to cool completely. This is a crucial step; the bars need to cool for at least 2 hours at room temperature, or even longer in the refrigerator, to allow the lemon filling to firm up and set properly. Attempting to slice them warm will result in a messy texture.
- Once fully cooled and set, use the parchment paper overhang to lift the entire slab of bars from the pan. Transfer to a cutting board and slice into desired squares using a sharp knife. For clean cuts, wipe your knife with a damp cloth between slices.
Tools You’ll Need
- 8×8-inch (20×20 cm) baking pan
- Parchment paper
- Large mixing bowls (2)
- Whisk
- Spatula or spoon
- Measuring cups and spoons
- Citrus zester
- Juicer (optional, for lemon juice)
- Wire cooling rack
- Sharp knife
Essential Success Tips
- Do not overmix the crumb mixture; overmixing can develop the gluten in the flour, resulting in a tougher crust. Mix only until the ingredients are just combined.
- Ensure your butter is fully melted but not scorching hot when combining with the sugar and vanilla; this helps achieve the perfect crumb texture.
- For the brightest lemon flavor, use freshly squeezed lemon juice and finely grated zest. Bottled lemon juice often lacks the vibrant acidity.
- Allow the bars to cool completely before slicing. This is paramount for the filling to set properly, preventing a gooey, messy outcome. Chilling in the refrigerator can speed this up and result in cleaner cuts.
- To achieve perfectly neat squares, use a warm, sharp knife. You can warm the knife by running it under hot water and wiping it dry between each cut.
Professional Cooking Secrets
- For an extra layer of complexity, infuse the melted butter for the crumb with a strip of lemon peel for 10 minutes before cooling slightly and using. Strain out the peel before mixing.
- If you want an even tangier filling, consider adding a tiny pinch of citric acid to the lemon mixture. This elevates the tartness without thinning the filling.
- Before pressing the crust, lightly toast the oats in a dry pan for a few minutes until fragrant. This adds a subtle nutty depth to the crumb that truly enhances the flavor profile.
Notes
- Storage: Store cooled lemon crumb bars in an airtight container at room temperature for up to 3 days, or in the refrigerator for up to 5 days. Chilling often enhances the firm texture of the filling.
- Freezing: Uncut bars can be frozen for up to 1 month. Wrap tightly in plastic wrap and then foil. Thaw in the refrigerator overnight before slicing.
- Variations: Experiment with lime juice and zest for a delightful lime crumb bar, or add a handful of shredded coconut to the crumb mixture for a tropical twist.
Frequently Asked Questions
Why did my lemon filling not set properly?
The most common reasons for a runny lemon filling are insufficient baking time, or not allowing the bars to cool completely. Ensure the filling has a slight wobble only in the very center when removed from the oven, and always allow at least 2 hours of cooling at room temperature, or chill in the refrigerator.
Can I use gluten-free flour for the crust?
Yes, you can substitute a 1:1 gluten-free all-purpose flour blend for the regular flour in the crust. Ensure your oats are certified gluten-free if you are strictly avoiding gluten. The texture may be slightly different but should still hold well.
How do I prevent my crumb topping from sinking?
The key is to have a slightly thicker filling and a crumb mixture that isn't too heavy or wet. The pre-baking of the crust helps create a stable base, and ensuring the reserved crumbs are just that—crumbs—and not a dense dough will keep them on top. Don't press the top crumbs down too hard.
Nutrition Facts (Per Serving)
Calories: Approximately 280-300 per bar (for 16 servings), Protein: 4g, Fat: 15g, Carbs: 35g. (These are estimates and can vary based on specific brands and exact ingredient quantities.)
Allergy Information
Contains dairy (butter, sweetened condensed milk, sour cream) and gluten (all-purpose flour, oats). Contains egg. For a gluten-free option, use a certified gluten-free all-purpose flour blend and certified gluten-free oats. Dairy-free substitutions for milk and sour cream are possible but may alter texture and flavor.
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