Step 1

Preheat oven to 350°F and grease and flour two 9-inch round cake pans.

Step 2

In a large bowl, whisk together the sugar, flour, cocoa powder, baking powder, baking soda, and salt.

Step 3

Add the eggs, milk, oil, and vanilla, and beat on medium speed with an electric mixer for 2 minutes.

Step 4

Gently stir in boiling water, then fold in chopped chocolate. Pour batter into the prepared pans. Bake until a toothpick inserted into the center comes out clean, 30-35 minutes.

Step 5

Let cool in pan 10 minutes before inverting onto a wire rack to cool completely.

Step 6

Note: To bake in a 9x13-inch baking dish, bake 35-40 minutes at 350°F.