Preheat your oven to 425°F (220°C) and grease four 6-ounce ramekins with butter. Dust them with cocoa powder to prevent sticking.

In a mixing bowl, whisk together the flour, cocoa powder, baking powder, and salt.

In a separate bowl, combine melted butter and sugar, whisking until smooth.

Add the eggs, egg yolk, vanilla extract, and red food coloring to the wet mixture. Mix until fully combined.

Gradually fold the dry ingredients into the wet mixture, stirring until just combined. Do not overmix.

Divide the batter evenly among the prepared ramekins. Push a chunk of dark chocolate into the center of each ramekin and cover it with batter.

Place the ramekins on a baking sheet and bake for 12-14 minutes. The edges should be firm, but the center should remain slightly jiggly.

Let the cakes cool for 2-3 minutes. Run a knife around the edges and carefully invert them onto serving plates.

Dust with powdered sugar and garnish with fresh berries if desired. Serve warm to enjoy the gooey molten center.