Preheat the oven to 350°F.
Grease a 9x13-inch baking dish thoroughly with nonstick cooking spray or butter.
In a large mixing bowl, combine the melted butter, granulated sugar, all-purpose flour, unsweetened cocoa powder, vanilla extract, baking powder, and eggs.
Mix until the brownie batter is smooth and fully combined.
Spread the brownie batter evenly into the prepared baking dish.
In a separate mixing bowl, combine the softened cream cheese, 1 large egg, and 1/3 cup granulated sugar.
Mix until the cheesecake mixture is smooth and creamy.
If using fresh cherries, remove the stems and pits, then slice the cherries in half.
If using canned cherry pie filling, use only the cherries and avoid adding excess filling.
Gently fold the prepared cherries into the cheesecake mixture.
Spread the cheesecake cherry mixture evenly over the brownie batter.
Using a butter knife, gently swirl the cheesecake mixture through the brownie batter.
Do not overmix; visible swirls of brownie and cheesecake should remain.
Bake for 35 to 45 minutes, or until a toothpick inserted into the center comes out clean or with only a few moist crumbs.
Remove the baking dish from the oven.
Allow the brownies to cool completely before slicing.
Top with additional cherries or whipped topping before serving, if desired.
Slice into squares and serve.