Preheat your oven to 425°F (220°C). Grease four ramekins generously with butter and dust with a little flour or sugar to prevent sticking. Set aside.

In a small saucepan over medium heat, combine heavy cream and butter. Stir until the butter melts. Remove from heat and whisk in powdered sugar, vanilla extract, and cornstarch until smooth. Let it cool for a few minutes. Then, transfer the mixture into a small bowl and place it in the freezer for about 10–15 minutes to firm up while you prepare the batter.

In a large mixing bowl, whisk together the whole eggs, extra yolks, and granulated sugar until pale, thick, and slightly frothy. This may take a few minutes by hand or quicker with an electric mixer.

Stir in the melted butter (make sure it’s cooled), milk, and vanilla extract into the egg mixture. Mix until combined.

Sift in the flour, baking powder, and salt. Gently fold the dry ingredients into the wet mixture using a spatula until the batter is smooth and lump-free.

Spoon a layer of cake batter into the bottom of each ramekin, filling about halfway. Take about a tablespoon of the chilled vanilla filling and place it in the center of each ramekin. Top with more batter until the ramekin is about ¾ full, completely covering the filling.

Place ramekins on a baking tray and bake in the preheated oven for 12 to 14 minutes. The edges should be set, but the center will remain slightly soft. Don’t overbake – this is what keeps the molten core!

Let the cakes rest for 1 minute after removing from the oven. Run a knife around the edges to loosen, then carefully invert onto serving plates. Dust with powdered sugar, add a scoop of vanilla ice cream or fresh berries if desired, and serve immediately.