Preheat oven to 350°F (175°C). Line an 8x8-inch pan with parchment paper, leaving overhang on two sides.

Melt butter in a medium saucepan over low heat. Remove from heat and stir in sugar until combined.

Whisk in eggs one at a time, then vanilla, until the mixture is smooth and glossy.

Sift cocoa powder, flour, salt, and baking powder together. Fold into the wet mixture until just combined — do not overmix.

Pour batter into the prepared pan and spread evenly. Bake for 22-25 minutes, until a toothpick inserted in the center comes out with a few moist crumbs. The edges will be set and the center slightly soft.

Let brownies cool in the pan for 10 minutes, then lift out using the parchment. Cool completely on a wire rack (about 30 minutes).

While brownies cool, make the sauce: In a small saucepan, combine heavy cream, chocolate chips, and corn syrup. Cook over low heat, stirring constantly, until smooth and warm. Do not boil.

Cut brownies into 6 squares. Place one brownie in each serving bowl. Top with a scoop of ice cream. Pour warm sauce over the top. Add whipped cream and a cherry if desired. Serve immediately.