Step 1: Preheat the Oven

1. Preheat your oven to 350°F (175°C). Grease an 8×8-inch baking pan or line it with parchment paper for easy removal.

Step 2: Prepare the Brownie Base

1. In a medium saucepan, melt the 1/2 cup of butter over low heat. Remove from heat and stir in the granulated sugar, eggs, and vanilla extract until well combined.
2. In a separate bowl, whisk together the cocoa powder, flour, salt, and baking powder.
3. Gradually add the dry ingredients to the wet mixture, stirring until just combined. Do not overmix.

Step 3: Bake the Brownies

1. Spread the brownie batter evenly in the prepared baking pan.
2. Bake in the preheated oven for 20–25 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs. Remove from the oven and let cool slightly.

Step 4: Prepare the Butterscotch Layer

1. In a saucepan over medium heat, combine the 1/2 cup of butter, brown sugar, and heavy cream. Stir until the mixture is smooth and bubbling, about 3–5 minutes. Remove from heat and stir in the vanilla extract and sea salt.

Step 5: Assemble the Brownies

1. Pour the butterscotch mixture over the slightly cooled brownies, spreading it evenly.
2. Sprinkle additional sea salt over the top.

Step 6: Cool and Serve

1. Allow the brownies to cool completely in the pan before cutting into squares. For best results, refrigerate for about 30 minutes to set the butterscotch layer.
2. Cut into squares and serve.