Preheat the oven to 350°F. Line a 9x9-inch baking pan with parchment paper and lightly spray with non-stick baking spray. Set aside.

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

In a medium saucepan, melt the butter with the oil and 1/3 cup of the sugar over medium heat, stirring frequently until the butter is fully melted. Remove from heat.

In a separate large bowl, whisk together the eggs and the remaining sugar until well combined, about 30 seconds.

Gradually add the warm butter mixture to the egg mixture, pouring in small amounts at a time while continuously whisking until fully blended.

Gently fold in the dry ingredients and chocolate chips using a rubber spatula. Be careful not to overmix—stop stirring as soon as the dry ingredients are no longer visible, as over mixing can make the brownies too cakey.

Pour the batter into the prepared pan and smooth out the top.

Bake for about 30 minutes, until the edges are set and the top is shiny with slight cracks.

Place the pan on a cooling rack and allow the brownies to cool completely before slicing.