Heat oven to 325 F. Lightly coat a 12-cup muffin tin with vegetable cooking spray.
Melt the chocolate and butter in a large bowl over a saucepan of simmering water.
Remove from heat. In another large bowl, beat the eggs and sugar at medium-high speed until light and fluffy.
Add the flour, baking powder, salt, and melted chocolate.
Mix with a spoon until well blended.
Divide the batter evenly into 8 muffin tins and bake until the cakes have just cooked through, about 15 minutes. The cakes will still look a bit moist on top.
