Prep. Start by preheating your oven to 350 and prepping baking pan or dish for nonstick.
Wet ingredients. In a mixing bowl, use a whisk to combine together the cocoa powder and melted butter until smooth and combined. Then whisk in the two sugars, eggs, and vanilla extract until combined.
Dry ingredients. Using a new bowl, use a fork or clean whisk to combine together the flour and cornstarch. Then slowly add these ingredients to the first bowl and mix until just combined.
Bake. Evenly spread the brownie batter in your prepared pan and then bake the brownies for 16-18 minutes or until the edges appear to be set. If you use the toothpick test, there will be a few crumbs.
Cool. Allow the brownies to fully cool.
Ganache Frosting. To make the ganache frosting, place the heavy cream into a microwave safe bowl and microwave for one minute. Carefully add in the the chocolate chips and then let the mixture sit for for a couple of minutes before mixing until smooth. You can then pour or evenly spread the ganache over the fully cooled brownies and top with the candies.
It is best to allow the ganache to fully set before slicing your brownies. You can refrigerate them to help speed this up.