Preheat oven to 425˚ F. Prepare your muffin tin by greasing the cups with butter and dusting them well with cocoa powder. This will prevent sticking.
In a microwave-safe bowl, add butter and chocolate. Microwave on high in 30 second bursts until butter and chocolate are just melted. Stir well between bursts and cook until the mixture is just melted.
In a small bowl whisk together eggs and egg yolks. In a medium bowl, whisk together flour, chocolate whey protein powder, powdered sugar, and salt.
Add half of the dry ingredients to the melted chocolate. Then stir in the eggs. Finally add the last of the dry ingredients and stir together until the mixture is smooth.
Pour batter into the prepared muffin tins, filling the tins almost to the top.
Bake chocolate cakes for 10-11 minutes, rotating the pan once halfway through. The chocolate cakes are done when they are starting to crack around the edges and cooked on top. They should still giggle a bit if you shake them slightly.
Remove the chocolate cakes from the oven and let them cool for a minute. Then carefully remove each cake from the muffin tin using a butter knife and/or spoon to help lift them out. Serve warm chocolate cakes with a dusting of powdered sugar and fresh raspberries!