Let two sticks of butter, eggs and milk warm to room temperature for about 10-15 minutes. In a medium bowl whisk flour, cocoa powder, salt and baking powder, set aside.
In a double boiler melt chocolate over a mild simmer until melted. If you don't have a double boiler you can use a small saucepan filled with a couple of inches of water. Bring water to a low simmer and place heatproof metal bowl over the pan. Make sure the bowl is big enough to hold itself over the pan and not touch the water. Stir chocolate until it is melted and let cool.
Using a mixer on low speed combine butter and sugars until light and fluffy. Add vanilla and eggs one at a time, then add cooled chocolate. Alternating flour mixture(dry ingredients) with milk (wet ingredient) starting and ending with the dry ingredients.
Place in cupcake lined cupcake pan and bake at 350 degrees for about 20-25 minutes depending on the oven. I would start checking them at about 15 minutes. Cupcakes are ready when a toothpick inserted into the center comes out clean.