Follow these straightforward steps to create your Key Lime Pie Bars – Browned Butter Blondie:

1. Preheat Your Oven: Begin by preheating your oven to 350°F (175°C). Line a 9×13 inch baking dish with parchment paper for easy removal later.
2. Brown the Butter: In a medium saucepan over medium heat, melt the unsalted butter. Continue cooking until it turns golden brown, stirring constantly. This will give a rich flavor to your bars. Remove from heat and let cool slightly.
3. Mix Sugars: In a mixing bowl, combine the browned butter with granulated sugar and brown sugar. Blend well until smooth.
4. Add Eggs and Vanilla: Incorporate the eggs and vanilla extract into the sugar mixture, mixing until fully combined.
5. Whisk Dry Ingredients: In a separate bowl, whisk together the flour, baking powder, baking soda, and salt.
6. Combine Mixtures: Gradually add the dry ingredients to the wet mixture, stirring until just combined. Be careful not to overmix.
7. Add Lime Zest: Gently fold in the lime zest for a burst of citrus flavor.
8. Prepare Lime Filling: In a separate bowl, whisk together the key lime juice and sweetened condensed milk until smooth.
9. Layering: Pour the blondie batter into the prepared baking dish, spreading it evenly. Next, pour the key lime mixture on top, spreading it evenly over the blondie batter.
10. Bake: Place in the preheated oven and bake for 25-30 minutes or until the edges are lightly golden, and a toothpick inserted into the blondie part comes out clean.
11. Cool Down: Remove from the oven and allow to cool in the pan for at least 15-20 minutes before lifting the bars out using the parchment paper.
12. Dust with Powdered Sugar: Once completely cooled, dust the top with powdered sugar for an added touch of sweetness before slicing into squares.