Preheat your oven to 400°F (204°C). Line a baking sheet with parchment paper, and spread halved cherries evenly across the sheet. Sprinkle a light layer of sugar over the cherries and roast for 10 minutes until tender.

Reduce the oven temperature to 325°F (163°C). Prepare an 8x8-inch baking dish by spraying it with non-stick spray and lining the bottom with parchment paper.

Sift together the all-purpose flour, Dutch process cocoa powder, cornstarch, and salt in a mixing bowl. Set aside.

In a separate mixing bowl, beat the sugar, eggs, and egg yolk on high speed for about 5 minutes until pale and frothy.

Melt the unsalted butter and let it cool slightly. Add the melted butter, oil, and vanilla extract to the egg mixture. Mix on low speed until combined.

Fold the dry ingredients into the wet mixture gently until just combined to maintain a fudgy texture.

Stir in half of the roasted cherries and chocolate chips into the batter.

Pour the batter into the prepared baking dish and bake for 40-50 minutes, checking for doneness with a toothpick.

Allow the brownies to cool completely in the pan for about 30 minutes on a wire rack.

Top with remaining roasted cherries before slicing into squares.