Preheat the oven to 350F. Lightly spray a 9x13 inch baking pan with baking spray.
In a large bowl, sift together the flour, baking soda, salt, and baking powder.
In a large mixing bowl or the bowl of a stand mixer with the paddle attachment, add the butter and sugars. Beat on medium speed until creamy. In a medium bowl, sift the cocoa powder. Add to the butter and sugar mixture. Beat on medium speed until very light and fluffy, about 5 minutes, stopping to scrape down the bowl a few times during mixing.
With the mixer running, add the eggs, one at a time, beating well after each addition. Stop to scrape down the bowl as needed throughout mixing. Beat in vanilla.
With the mixer turned off, add a cup of the flour mixture followed by half of the milk and half of the sour cream. Continue to alternate between the flour, milk, and sour cream until well combined. Scrape down the bowl.
After all the flour, milk, and sour cream are well combined carefully whisk in the hot coffee. Pour the batter into the prepared cake pan.
Bake for 40 to 45 minutes or until the cakes are starting to pull away from the sides of the pans and a tooth pick comes out clean with a small amount of crumbs. You don't necessarily want the toothpick to be completely clean as that can indicate the cake is too done. Let the cake cool completely in the pan.