Preparation Steps

• Preheat your oven to 350°F (175°C). Grease and flour an 8x8 inch baking pan.
• In a medium bowl, melt the butter for the brownie base. Stir in the granulated sugar until well combined.
  0.5 cup unsalted butter
• Beat in the eggs one at a time, then stir in the vanilla extract.
  0.5 cup unsalted butter
• In a separate bowl, whisk together the flour, cocoa powder, baking powder, and salt.
  0.5 cup unsalted butter
• Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix.
• Spread the brownie batter evenly into the prepared pan.
• To make the French silk filling, melt the chopped semisweet chocolate in a heatproof bowl over a double boiler or in the microwave in 30-second intervals, stirring until smooth.
  0.5 cup unsalted butter
• In a medium bowl, cream together the softened butter and powdered sugar until light and fluffy.
  0.5 cup unsalted butter
• Beat in the egg yolk and vanilla extract until well combined.
  0.5 cup unsalted butter
• Gently fold the melted chocolate into the butter mixture until smooth.
• Pour the French silk filling over the brownie batter and swirl gently with a knife to create a marbled effect.
• Bake for 30-35 minutes, or until a toothpick inserted into the center comes out with moist crumbs attached.
• Let cool completely in the pan before cutting into squares.