Preheat the oven to 350 degrees F (175 degrees C). Grease a 13x9-inch baking pan.

For the filling: Beat cream cheese, sugar, flour, egg, and vanilla extract in a bowl with an electric mixer until creamy.

For the brownies: Combine sugar, flour, cocoa powder, black onyx cocoa powder, salt, and baking powder in a large bowl. Beat together oil, eggs, corn syrup, and vanilla extract in a separate bowl. Pour into flour mixture and mix to combine. Spread 3/4 of the batter into the prepared baking pan.

Mix 1/4 cup chopped morello cherries into the batter in the pan. Spread remaining cherries across the top of the brownie batter in one layer. Pour cream cheese filling over the cherries. Spread remaining brownie batter on top of the cream cheese filling. Draw a knife through the batter to create swirls.

Bake in the preheated oven until top is dry and edges have started to pull away from the sides of the pan, 25 to 27 minutes. A toothpick inserted in the center should come out clean. Let cool completely before slicing.