Instructions

• Preheat oven to 350°F. Line an 8" or 9" round baking pan with foil, leaving an overhang for lifting the cake out later, and spray the foil with nonstick cooking spray.
• Make the brownie batter: place 1/4 cup (57 g) unsalted butter and 2 ounces (57 g) unsweetened chocolate in a large, heatproof bowl. Microwave on high in 30-second increments, stirring between each, until melted and smooth (about 1–2 minutes total).
• Stir 1/4 cup (59 ml) vegetable oil, 3/4 cup (350 g) granulated sugar, and 1/4 cup (59 ml) light Karo Syrup into the melted chocolate mixture until combined.
• Stir in 2 large eggs and 2 teaspoons vanilla extract until the mixture is smooth. Then stir in 1/2 teaspoon baking powder and 1/2 teaspoon salt until evenly distributed.
• Gradually add 2/3 cup (82 g) all-purpose flour and stir until just combined. Do not overmix.
• Fold in 2 cups chopped candy until evenly distributed through the batter.
• Pour the batter into the prepared pan and smooth the top with a spatula. Bake for 30–35 minutes, testing by inserting a toothpick about 2 inches from the edge: it should come out with just a few moist crumbs (not wet batter).
• Cool the brownie completely in the pan on a wire rack. Cooling completely is important so the frosting will set properly.
• Make the frosting: put 2/3 cup (113 g) semi-sweet or milk chocolate chips, 1 1/2 tablespoons (21 g) unsalted butter, and 1 teaspoon vanilla extract in a heatproof bowl and set aside.
• In a small saucepan, combine 1/2 cup (118 ml) heavy whipping cream and 3 tablespoons (45 ml) light Karo Syrup. Heat over medium, stirring often, until it comes to a boil.
• Immediately pour the hot cream mixture over the chocolate mixture. Let sit 30–60 seconds, then whisk until smooth. Let the frosting sit at room temperature until it thickens slightly and is spreadable (about an hour). If you need it thicker sooner, you can chill it briefly until it reaches the desired consistency.
• Using the foil overhang, lift the cooled brownie from the pan and transfer it to a cake plate. Pour the slightly thickened frosting over the top and spread or smooth as desired. Sprinkle additional chopped candy on top as a garnish.
• Let the frosting set for several hours at room temperature (chilling speeds this up). You may have some frosting left over. Store the cake loosely covered for up to 3 days.