Preheat your oven to 425°F (220°C) and prepare your ramekins or muffin tin by greasing with unsalted butter and dusting with flour.

In a microwave-safe bowl, combine 6 ounces of dark chocolate and ½ cup of unsalted butter. Heat in 30-second intervals until smooth.

In a separate bowl, whisk together 2 large eggs and ¼ cup of sugar until pale and thickened, about 3 minutes.

Gently fold the melted chocolate mixture into the egg mixture until fully incorporated.

Fold in ¼ cup of all-purpose flour and 1 teaspoon of vanilla extract until just combined.

Spoon the batter into prepared ramekins, filling them about 2/3 full.

Bake for 12 to 14 minutes, until the edges are firm but the centers are still jiggly.

Let the cakes cool for 1 minute, then carefully invert onto plates.

Serve immediately with vanilla ice cream, whipped cream, or fresh berries.