Preheat oven to 425°F. Grease two 6-8 oz oven-proof ramekins or custard cups with butter or nonstick baking spray.

In a saucepan set over medium low heat, melt chocolate butter until smooth. Remove from heat and stir in sugar, and then eggs one at a time. Stir in liquor if using.

Add flour and salt and fold in with a spatula just until combined. Do not overmix.

Divide batter between the two ramekins and bake for 10-11 minutes, or just until the centers of the cakes appear set and are no longer moist. Do not overbake or you'll ruin the soft molten center.

Let cakes sit in the ramekins for 1-2 minutes, then invert onto a plate and remove the ramekin. The cakes will continue cooking in the ramekin out of the oven, so don't let it sit too long.

Serve immediately with a scoop of ice cream or whipped cream, fresh berries, chocolate sauce, or however you'd like.