Creating Key Lime Pie Bars – Browned Butter Blondie is a delightful process. Follow these steps for the best outcome:

1. Preheat the Oven: Start by preheating your oven to 350°F (175°C). Grease and line a 9×13 inch baking pan with parchment paper for easy removal.

2. Brown the Butter: In a saucepan over medium heat, melt the butter. Continue cooking, stirring frequently, until it turns golden brown and has a nutty aroma. Remove from heat and let it cool slightly.

3. Mix the Blondie Batter: In a large mixing bowl, combine the browned butter and brown sugar. Stir until well blended. Add eggs and vanilla extract, mixing until smooth. Incorporate the flour, baking powder, and salt, stirring until just combined.

4. Spread the Blondie Base: Pour the blondie batter into the prepared baking pan, spreading it evenly across the bottom.

5. Prepare the Key Lime Filling: In a separate bowl, whisk together the sweetened condensed milk, key lime juice, egg yolks, and lime zest until smooth.

6. Layer the Filling: Pour the key lime filling carefully over the blondie base. Use a spatula to spread it evenly, ensuring even distribution.

7. Bake: Place the pan in the oven and bake for 25-30 minutes, or until the filling is set and slightly jiggles in the center. Allow to cool in the pan before refrigerating for at least 1 hour.