Preheat your oven to 350°F (175°C). Grease four ramekins with butter or non-stick spray, and lightly dust with cocoa powder to prevent sticking.
In a large bowl, sift together 1/2 cup unsweetened cocoa powder, 1/2 cup all-purpose flour, 1/2 cup granulated sugar, 1/2 teaspoon baking powder, and a pinch of salt.
In a separate bowl, whisk together 2 large eggs, 1/4 cup melted unsalted butter (cooled slightly), 1/4 cup milk, and 1 teaspoon vanilla extract until smooth and frothy.
Gradually add the wet mixture to the dry ingredients, stirring gently with a spatula or whisk until just combined. Avoid overmixing.
Divide the batter evenly among the prepared ramekins. Press a few chocolate chips into the middle of each cake if desired for a molten center.
Place the ramekins on a baking sheet and bake for 12-15 minutes. The edges should be set but the center slightly soft and jiggly.
Let the cakes cool for 2-3 minutes before carefully running a knife around the edges. Invert each ramekin onto a plate and dust with powdered sugar. Serve immediately.