Preheat your oven to 350°F (175°C) and prepare a 9-inch round cake pan by greasing it or lining with parchment paper.

In a large mixing bowl, whisk together melted unsalted butter and granulated sugar until smooth. Add the eggs one at a time and mix in the vanilla extract.

In another bowl, sift together cocoa powder, flour, salt, and baking powder to incorporate air.

Gradually add the dry ingredients to the wet ingredients, stirring gently until combined.

Fold in the chocolate chunks until evenly distributed.

Pour the batter into the prepared pan and spread evenly. Bake for 25-30 minutes until a toothpick comes out clean or with some moist crumbs.

Let the cake cool in the pan for 10 minutes before transferring it to a wire rack to cool completely.