Preheat your oven to 350°F (175°C). Grease and line an 8x8-inch baking dish with parchment paper.

In a medium bowl, whisk together flour, cocoa powder, baking powder, and salt.

In a large bowl, combine granulated sugar and dark brown sugar. Add melted butter and mix until smooth.

Add beaten eggs and vanilla extract to the mixture, whisking until well combined.

Pour dry ingredients into wet mixture gradually, mixing gently until just combined. Fold in chopped dark chocolate.

Pour the brownie batter into the lined baking dish and spread evenly.

Bake for 20-25 minutes until edges are set and center is slightly soft.

Prepare the butterscotch sauce by combining white sugar, dark brown sugar, and water in a saucepan and bring to a boil.

Once the mixture turns golden, remove from heat and whisk in butter, cream, sea salt, and vanilla extract.

Drizzle butterscotch sauce over cooled brownies, sprinkle with sea salt flakes, and allow to cool completely before slicing.