Preheat the oven to 425°F. Grease the ramekins with butter and set them aside.
In a large microwave-safe bowl, combine the butter and chocolate and microwave in 30-second increments, stirring as needed, until melted.
Whisk in the salt and vanilla extract.
Whisk in the eggs and egg yolks then whisk in the confectioners’ sugar and flour just until combined.
Divide the batter evenly among the greased ramekins then place them on a baking sheet.
Bake the lava cakes for 10 to 12 minutes until the cake it set but still slightly jiggly in the centers. (Note: Make the raspberry sauce while the lava cakes are baking.)
Remove the lava cakes from the oven and allow them to sit for 5 minutes.
Carefully run a knife around the inside edge of each ramekin then invert each lava cake onto a serving plate.