Preheat the oven: Begin by preheating your oven to 425°F (220°C). Lightly butter four ramekins (about 6 oz size) and dust with flour, tapping out any excess. This will prevent the cake from sticking.

Melt the chocolate and butterscotch: In a medium saucepan, combine the butterscotch chips, dark chocolate, and butter. Over low heat, stir constantly until the mixture is smooth and melted. Once it’s fully melted, remove it from the heat and let it cool slightly.

Mix eggs and sugar: In a separate bowl, whisk the eggs, egg yolks, sugar, and vanilla extract together until light and frothy, about 2 minutes. This helps create a lighter texture for the cake.

Combine the wet ingredients: Gradually add the slightly cooled chocolate-butterscotch mixture to the egg mixture, stirring gently until fully incorporated.

Add the dry ingredients: Sift in the flour and pinch of salt, mixing just until everything is combined. Be careful not to overmix, as this can make the cake tough.

Add the bourbon: Stir in the bourbon. It adds that rich, warming flavor that makes this cake so special for the holiday season.

Fill the ramekins: Divide the batter evenly between the prepared ramekins. Make sure to leave about 1/2 inch of space at the top, as the cake will rise as it bakes.

Bake: Place the ramekins on a baking sheet and bake in the preheated oven for 12-14 minutes, or until the edges are set but the center is still soft. The cake should jiggle slightly when you shake the pan, but the outside should be firm.

Serve: Let the cakes sit for 2 minutes before running a knife around the edges to loosen them. Carefully invert onto serving plates. Dust with powdered sugar and serve with whipped cream or vanilla ice cream for an extra indulgent touch.