Step-by-Step Instructions

1. 1.Melt Chocolate and Butter

   Place the butter and dark chocolate in a saucepan. Melt them together over very low heat, stirring occasionally, until smooth. Ensure the temperature does not exceed 40°C to prevent the chocolate from burning or seizing.

2. 2.Whisk Eggs and Sugar

   In a separate large bowl, crack the 4 eggs. Add the 100g of sugar to the eggs and whisk vigorously until the mixture is well combined and slightly pale.

3. 3.Combine Chocolate Mixture with Egg Mixture

   Pour the melted chocolate and butter mixture into the egg and sugar mixture. Whisk thoroughly until all ingredients are fully incorporated and the batter is smooth.

4. 4.Incorporate Flour

   Add the 40g of flour (approximately two heaped tablespoons) to the chocolate batter. Mix gently until just combined. The flour helps the cake set around the edges while keeping the center gooey.

5. 5.Prepare Molds

   Generously butter the inside of your ramekins or molds with softened butter. Then, dust them with flour, tapping out any excess. This 'chemisage' prevents the lava cakes from sticking.

6. 6.Fill Molds

   Carefully pour the chocolate batter into the prepared ramekins, filling them about three-quarters full.

7. 7.Bake the Lava Cakes

   Preheat your oven to 180°C (350°F). Place the filled ramekins on a baking rack in the oven. Bake for 8 minutes. The center should still be slightly wobbly when gently touched, indicating a molten core.

8. 8.Demold and Serve

   Once baked, carefully remove the ramekins from the oven. Allow them to cool for a minute or two. Place a plate over the ramekin and invert it to demold the lava cake. Cut into the cake to reveal the flowing chocolate center. Serve immediately.