Preheat your oven to 400°F (200°C). Arrange the halved fresh cherries in a single layer on a lined baking sheet and sprinkle lightly with sugar. Roast for about 10 minutes and then set aside to cool.

Lower the oven temperature to 325°F (160°C). Spray an 8x8-inch baking pan with non-stick spray and line with parchment paper.

In a mixing bowl, sift together all-purpose flour, cocoa powder, cornstarch, and salt. Whisk to combine and set aside.

In a separate bowl, beat sugar, eggs, and egg yolk on high speed for about 5 minutes. Gradually add melted butter, oil, and vanilla extract, mixing on low until just combined.

Fold the dry ingredients into the wet mixture until just combined. Fold in half of the roasted cherries and chocolate chips.

Pour the batter into the prepared pan and bake for 40-50 minutes until edges are set. A toothpick should come out with moist crumbs.

Let the brownies cool in the pan for about an hour. Top with remaining roasted cherries before slicing.