Heat oven to 425 degrees Fahrenheit; grease four ramekins.

Microwave the butter and chocolate in a bowl until melted and smooth.

Whisk in the powdered sugar, then the eggs and egg yolks. Stir in the flour.

Divide half the batter among ramekins. Add one tablespoon cookie butter to each center.

Cover the cookie butter with the remaining chocolate batter.

Bake for 12 minutes until the edges are firm but the center is soft. Invert onto a plate and serve warm.