Preheat your oven to 425°F (220°C). This high temperature is essential for creating that perfect molten center.

Grease four 4-ounce ramekins with butter or cooking spray. Dust them lightly with flour to prevent sticking. Place the ramekins on a baking tray for easy handling.

In a microwave-safe bowl, combine the unsalted butter and white chocolate chips. Microwave in 30-second intervals, stirring after each, until smooth and completely melted. Allow it to cool slightly.

In a separate bowl, whisk together the eggs, egg yolks, granulated sugar, and vanilla extract until the mixture is thick and pale. This aeration will help create a light texture.

Slowly pour the melted chocolate mixture into the egg mixture, stirring gently to combine. Be careful not to cook the eggs.

Sift the flour and salt into the chocolate-egg mixture. Gently fold until just combined, ensuring not to overmix.

Evenly distribute the batter among the prepared ramekins, filling each about ¾ full.

Bake in the preheated oven for 12-15 minutes. The edges should be firm, while the center remains soft and jiggly. Keep an eye on them to avoid overcooking.

Once baked, remove the ramekins from the oven and let them rest for 1-2 minutes. This will make it easier to unmold them.

Carefully run a knife around the edges of each ramekin to loosen the cake. Invert onto a plate and gently lift the ramekin off. Dust with powdered sugar, and add fresh berries or a scoop of vanilla ice cream if desired.