Preheat your oven to 400°F (200°C). Line a baking sheet with parchment paper and arrange the halved cherries on it. Sprinkle them with sugar and roast for 10 minutes until tender and caramelized.

Lower the oven temperature to 325°F (163°C). Grease an 8x8 inch baking dish and line it with parchment paper.

In a bowl, sift together the flour, cocoa powder, cornstarch, and salt. Set aside.

In a separate bowl, beat the eggs, egg yolk, and sugar for about 5 minutes until pale and fluffy.

Melt the butter and let it cool. Mix it with canola oil and vanilla extract, then combine this with the egg mixture.

Gently fold the dry mixture into the wet ingredients until nearly combined, then stir in half of the roasted cherries and chocolate chips.

Pour the batter into the prepared baking dish and bake for 40 to 50 minutes. A toothpick should come out with moist crumbs.

Allow the brownies to cool completely. Top with remaining roasted cherries before serving.