Preheat the oven to 350-degrees.

Grease or spray two 9-inch cake pans and line the bottoms with rounds of parchment paper.

Chop the chocolate and melt it in the microwave or in a double boiler, being careful not to burn it. Set aside.

1. Chop the chocolate and melt it in the microwave or in a double boiler, being careful not to burn it. Set aside.
   
   
2. Sift the cocoa, flour, baking soda, baking powder and salt together in a medium bowl.
   
   
3. Combine the sugar and butter in the bowl of a stand mixer and beat on medium speed for 5 to 6 minutes. Scrape the bowl and continue beating until the mixture is light and fluffy.
   
   
4. Add the eggs, one at a time, scraping the bowl after each addition. The batter may look curdled at this point, which is fine.

5. Add the melted, cooled chocolate and vanilla and mix on medium speed for 30 seconds.
   
   
6. With the mixer on low, add the dry ingredients and the milk in several alternating additions, mixing for about 30 seconds after each.
   
   
7. Remove the bowl from the mixer and use a spatula to make sure the batter is fully blended.
   
   
8. Pour the batter into the prepared pans.
   
   
9. Bake until the cakes spring back in the center when lightly pressed, or a tester inserted in the center comes out clean, 25–30 minutes.
   
   
10. Cool the cakes on a wire rack for 10 minutes. Remove them from the pans and cool completely.
    
    
11. Fill and frost as desired.