Ingredients - brownie layer
For the brownie layer, you'll need flour, cocoa powder, sugar, brown sugar, eggs, butter, chocolate, and vanilla.
Ingredients - blondie layer
For the blondie layer, you'll need flour, baking powder, salt, butter, brown sugar, chocolate, egg, and vanilla..
Make the brownie batter
Start by melting the sugars, butter, and chocolate together. Whisk in the eggs and vanilla. Then, fold in the flour, cocoa powder, and salt. Lastly, fold in the chopped chocolate.
Make the blondie batter
Start by whisking together the melted butter and brown sugar. Whisk in the egg and vanilla, then fold in the dry ingredients. Lastly, fold in the chocolate.
Add the brownie layer
Spread about 2/3 of the brownie batter in a 9x9 pan.
Add the blondie layer
Add all of the blondie batter in large dollops on top of the brownie layer. Fill in the gaps with the remaining brownie batter.
Bake the brownie blondies at 350 degrees F for about 30 minutes.
Cool before cutting
Allow them to cool completely before cutting. Top with flaky sea salt and serve!