Ingredients

For the Crust & Topping:

• 7 tablespoons (99g) unsalted butter, softened to room temperature
• 3/4 cup (150g) light or dark brown sugar, packed
• 1 teaspoon vanilla extract
• 1 cup (125g) all-purpose flour (spooned & leveled)
• 1 teaspoon baking powder
• 1/4 teaspoon salt
• 1 cup (85g) old-fashioned oats or quick oats (not instant)

For the Lemon Filling:

• 1 can (14 ounces) full-fat sweetened condensed milk
• 6 tablespoons (90ml) lemon juice (from about 2 lemons)
• 1 tablespoon lemon zest (from about 1 lemon)

Instructions:

1. Prepare the oven and pan: Preheat the oven to 350°F (177°C). Line an 8-inch square baking pan with parchment paper for easy removal of the bars.  
2. Make the crust and topping:  
   • Using a handheld or stand mixer with the paddle attachment, beat the softened butter and brown sugar on medium-high speed until fully combined (about 1 minute).
   • Scrape down the sides of the bowl, then add the vanilla extract. Beat again on medium-high for 30 seconds until incorporated.
   • Add the flour, baking powder, salt, and oats. Mix on medium speed until combined. The mixture should be crumbly and dry, forming between 3–3.5 cups of mixture in total.
3. Form the crust:  
   • Press slightly more than half of the crumble mixture into the bottom of the prepared pan to form the crust. (You want slightly more for the crust than for the topping.)
   • Bake for 12 minutes, then remove from the oven.
4. Make the lemon filling:  
   • In a medium bowl, whisk together the sweetened condensed milk, lemon juice, and lemon zest until smooth and thick.
5. Assemble the bars:  
   • Pour the lemon filling over the pre-baked crust while it’s still hot, and spread it evenly.
   • Sprinkle the remaining crumble mixture on top of the lemon filling.
6. Bake:  
   • Return the bars to the oven and bake for an additional 22–25 minutes or until the edges are lightly golden and the center is set. Be careful not to over-bake.
7. Cool and cut:  
   • Once done, remove from the oven and let the pan cool completely on a wire rack.
   • Once cooled, use the parchment paper to lift the bars out of the pan. Slice into squares.
8. Storage:  
   • Store the leftover bars at room temperature for up to 2 days or refrigerate for up to 1 week.

Freezing Instructions:

• To freeze, place cut bars in a single layer, separated by parchment paper, in a freezer-safe container. They will keep for up to 3 months. To enjoy, thaw overnight in the refrigerator and bring to room temperature before serving.

• Sweetened Condensed Milk: Make sure you’re using full-fat sweetened condensed milk (not evaporated milk) for the filling to set properly. Fat-free versions won’t work.
• Doubling the Recipe: You can easily double the recipe. Simply double all the ingredients and bake in a 9x13-inch pan. Increase the crust pre-bake time to 18 minutes, and bake the filled bars for 35 minutes, or until set.