Preheat oven to 450F
Butter and flour 4 ramekins and place on a baking sheet
Combine the butter and chocolate in a double boiler and melt over low heat, stirring until smooth
Remove from heat and set aside
In a large mixing bowl, beat the eggs and sugar on medium speed until thick and pale yellow
Add the melted chocolate mixture, cake flour, baking powder, and salt
Fold until well combined
Transfer the batter into the prepared ramekins
Bake for 6-8 minutes or until the sides of the cakes are firm set, but the center is jiggly
Allow to cool in the ramekins for a minute
Place a dessert plate over each ramekin and flip it over, carefully remove the ramekin
Dust with powdered sugar and garnish with mint, if desired
Serve immediately
