Preheat oven to 400.
Set 6 small (6-ounce) ramekins on a baking sheet.
Brush the insides of ramekins with melted butter; set aside.
Set up a double boiler and melt chocolate.
In the meantime, combine egg yolks, 1/4 cup sugar, and liqueur in your mixer's bowl; beat on high speed until pale yellow and thick.
Add melted chocolate into the yolks and continue to beat until well combined. Set aside.
In a separate mixing bowl, combine egg whites and 2 tablespoons sugar; using clean beaters, beat until the egg whites are shiny and firm.
Stir one-third of the whites into the chocolate mixture; stir to combine.
Pour the chocolate mixture into the egg whites-mixture; fold until thoroughly combined.
Spoon the batter into the previously prepared ramekins, filling each ramekin to the top.
Bake on the lower rack of your oven for 10 minutes.
Remove from oven.
Garnish with powdered sugar, chopped hazelnuts and mini chocolate chips.