1-First, preheat your oven to 350 degrees Fahrenheit and line an 8×8 inch metal baking pan with parchment or foil, then spray it with cooking spray. This sets the stage for even baking and easy removal.

2-Next, in a large microwave-safe bowl, melt the 10 tablespoons of unsalted butter for about 90 seconds on high. Stir in the 1 cup granulated sugar, 1/3 cup packed light brown sugar, and 3/4 cup plus 2 tablespoons unsweetened cocoa powder. Let this mixture cool slightly if it’s too hot to handle.

3-Then, add the 2 large eggs plus 1 egg yolk, 1 tablespoon corn syrup, and a dash of vanilla extract to the butter mixture, stirring everything well until smooth. Gradually mix in the 2/3 cup all-purpose flour, 1 tablespoon cornstarch, 1/4 teaspoon baking powder, and 1/2 teaspoon salt until just combined the batter should be thick and fudgy.

4-Pour the batter into your prepared pan and bake for 25 minutes. Let the brownies cool completely in the pan before moving on. For the frosting, microwave the 1/2 cup heavy cream for 1 minute, add the 1 1/2 cups chocolate chips, let it sit for 3 minutes, then stir until smooth. Spread the frosting over the cooled brownies and top with candy-coated chocolate chips or sprinkles, then refrigerate for 1 to 2 hours until set.