Step 1: Preheat your oven to 350°F (175°C).
Step 2: Melt the chocolate and 1/4 cup of butter in a saucepan over low heat.
Step 3: Combine the melted chocolate mixture with brown sugar and 1 egg in a bowl. Fold in flour until just combined.
Step 4: Cream the remaining butter and sugar, then add eggs one at a time. Fold in flour, baking powder, and milk.
Step 5: Grease the cake pan and pour in the brownie batter, followed by the cake batter.
Step 6: Bake for 25-30 minutes until a toothpick comes out with a few moist crumbs.
Step 7: Let cool in the pan for 10 minutes, then transfer to a wire rack to cool completely.
