Heat your oven to 350ºF (180ºC) and prepare two 9-inch (23-cm) cake pans with parchment paper and a light coating of baking spray.
In a big bowl, mix together flour, baking powder, baking soda, cocoa, and salt. Set aside.
Dissolve instant coffee in hot water and set it aside.
Use an electric hand mixer or a stand mixer to beat butter until creamy (about 3-4 minutes). Add sugar and beat on high for another 4 minutes until it's creamy and light. Add sour cream, oil, vanilla, vinegar, and the coffee mixture, beating for about 1 minute.
On low speed, add the flour mixture in three parts, alternating with buttermilk, starting and ending with the flour. Mix until just combined, around 30-45 seconds. Don't overmix.
Pour the batter into the prepared pans.
Bake for around 35-40 minutes, or until a toothpick inserted in the center comes out clean.
Take the cakes out of the oven and let them cool in the pans on wire racks for 10 minutes before removing them. Let the cakes cool completely, right-side up, on a wire rack before taking off the parchment paper.