Preheat oven to 400*
Grease and dust with flour, or spray with nonstick cooking spray, or line four large muffin cups.
Using a double boiler, or a large glass mixing bowl over a boiling pan of water melt butter and chocolate chips. Continue stirring until smooth and remove from heat. DO NOT allow to over heat, only heat enough to melt smoothly.
Add flour, sugar, eggs, and egg yolks to the melted chocolate mixture.
Divide batter into four prepared baking cups.
Bake about 10 minutes, until crusty layer forms and middle isn't jiggling when gently moved. Do not over bake, or you will not have Lava.
Allow to cool for about 5 minutes. Slide butter knife gently along the edge to make sure cake is not sticking. Gently lift cake out and invert on plate, or invert pan on plate to remove cakes. Serve warm.
Topping ideas: powdered sugar, drizzle frosting, ice cream, drizzle flavored syrup, whipped topping.
