Prepare a bundt pan by spraying it with cooking spray and dusting it with a 1-2 tablespoons of flour. Discard any remaining flour in bundt pan. Set bundt pan aside. In a medium bowl, sift together the cake flour, baking powder, and salt in a bowl. Set aside.

In a separate medium bowl, combine 1/2 cup of sugar, cocoa powder, coffee granules (if using) and water. Whisk until all the lumps have been worked out of the mixture. Set aside.

In the bowl of an electric stand mixer, fitted with the paddle attachment, beat the melted butter and sugar together for 1 minute. Add in the vanilla extract. Once combined, add the eggs and allow to beat one at a time until combined. Stop the mixer and scrape down the sides as necessary. Once eggs have been incorporated, beat the mixture until it becomes lighter in color and fluffy. The cake batter should look like pancake batter but thinner.

With the mixer speed on low, add in the flour in 1/3 of the flour mixture, then 1/2 of the milk, repeating with 1/3 of the flour, the rest of the milk, and follow with the remaining 1/3 of the flour mixture. Do not overmix the batter. Add 2 cups of this batter to the cocoa mixture in step 2. Stir just until combined. Position a rack in the center of the oven and preheat the oven to 350º F.

Using an ice cream scoop or 1/4 measuring cup, pour two scoops of the vanilla mixture into bundt pan. Following with one scoop of chocolate mixture. Repeat and continue to alternate with vanilla and chocolate until the pan is filled.

Bake the zebra poundcake with 55-65 minutes or until a cake tester inserted in the center comes out mostly clean. Cool the cake on a wire rack for 15-20 minutes before inverting and cooling completely.