Preheat the oven to 350 degrees Fahrenheit. Spray three 6-inch cake pans with nonstick cooking spray that contains flour. Set aside.

In a large bowl, beat the butter and granulated sugar together for 1 to 2 minutes until creamy.

Add the eggs one at a time, mixing well after each addition. Add the vanilla extract with the last egg and continue mixing until the batter is light and fluffy.

In a separate bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt.

In another bowl or measuring cup, stir together the brewed coffee and buttermilk.

Add one-third of the flour mixture to the butter mixture and mix until combined. Add some of the coffee and buttermilk mixture and mix again. Continue alternating between the dry ingredients and the liquid ingredients, ending with the flour mixture. Mix until fully combined but do not overmix.

Divide the batter evenly between the prepared cake pans.

Bake for 20 to 25 minutes, or until a toothpick inserted into the center comes out clean.

Let the cakes cool in the pans for about 10 minutes, then turn them out onto a cooling rack to cool completely.

In a large bowl, beat the butter for 1 to 2 minutes until it becomes lighter in color and smooth.

Add 3 cups of powdered sugar, the vanilla extract, and the espresso or coffee.

Beat until smooth and creamy. Add more powdered sugar as needed to reach your desired consistency for spreading and piping.

Place the first cake layer on a serving plate with the top side facing up.

Spread about one-third to one-half cup of frosting evenly over the top.

Add the second cake layer with the top side facing down. Spread another layer of frosting.

Place the final cake layer with the bottom side facing up.

Spread a thin layer of frosting over the entire cake to create a crumb coat.

Refrigerate the cake for 20 to 30 minutes to set the crumb coat.

Remove from the refrigerator and apply a final smooth layer of frosting over the top and sides.

Reserve about one-half to three-quarters cup of frosting for piping a decorative border.

Heat the heavy cream in a small saucepan until it just begins to simmer.

Pour the hot cream and espresso over the white chocolate chips in a heat-safe bowl.

Let sit for 2 minutes, then whisk until smooth.

Allow the ganache to cool until it is slightly thickened but still pourable.

Spoon small amounts of ganache around the edges of the cake, allowing it to drip down the sides slowly.

Pipe the reserved frosting around the top edge of the cake for a decorative border.

If desired, pour any remaining ganache into the center of the cake.