Ingredients

• Cooking spray or butter for greasing
• ¾ cup semi-sweet chocolate chips
• ½ cup (1 stick) butter
• 1 cup powdered sugar
• ½ teaspoon pure vanilla extract
• 2 eggs
• 2 egg yolks
• 6 Tablespoons flour

Instructions

1. Preheat the oven to 425 degrees.
2. Butter or spray with cooking spray four custard or soufflé dishes (they’re usually 3/4-cup-sized). Place them on a baking sheet.  If you don’t have custard dishes, use a regular size muffin pan and make seven smaller cakes (OR if you have a jumbo muffin pan, you can still make four larger cakes).
3. Melt the chocolate chips together with the butter in the microwave for 1 minutes, or until the butter is melted (only the butter needs be melted at this point). Stir with a whisk until the warm butter has melted the chocolate chips.
4. Stir in sugar and vanilla until well blended.
5. Whisk in eggs and egg yolks.
6. Stir in flour and mix well.
7. Divide batter into the buttered dishes (or the muffin pan). 
8. If using custard cups or a jumbo muffin pan, bake the cakes for approximately 10-12 minutes or until the sides are firm.  If using a regular sized muffin pan, bake the cakes for about 8 minutes or until the sides are firm.  Do not over-bake them or the center of the cakes will be dry.
9. Let stand for 1 minute. 
10. Carefully run a small knife around the cakes to gently loosen.
11. Cover each custard dish with a small plate and then flip the cake onto the plate.  Or if using a muffin pan, cover the pan with a baking sheet, then, holding tightly together the edges of the muffin pan and the baking sheet, with one hand on each end, flip the cakes over onto the sheet.
12. Gently, with a large, flat spatula, transfer the cakes onto little plates.
13. Serve immediately.