Grease and flour a 10 inch (16 cup) bundt cake pan
Lower the oven rack to the next to lowest position. Preheat the oven to 325 degrees.
In a separate bowl whisk the flour and baking powder to combine, set aside.
Beat the butter until smooth and creamy. Gradually add the sugar and beat on medium speed for 3 to 5 minutes until it is light and fluffy, may take longer if using a hand mixer.
Add the vanilla. Add the eggs one at a time beating after each until the yolk is blended in.
Add the flour mixture alternately with the milk, beginning and ending with the flour mixture (3 additions of dry ingredients and 2 additions of milk). Mix just until combined, scraping the sides and bottom of bowl.
At this point, you will remove 2 ½ cups of the cake batter and put into another bowl. Add the cocoa and red food coloring and stir to combine.
Using a small cookie scoop (1 ½”) or a Tablespoon, place scoops of the plain batter into the prepared pan, top this with the red batter, alternating each row until the batter is used. You could use a table knife to swirl slightly, or just leave in layers of color.
Bake at 325 degrees for 1 hour to 1 hour and 5 minutes. If using an aluminum tube pan, the baking time will be longer. A toothpick or thin skewer inserted in the cake should come out clean or with just a few crumbs attached. Let cool in the pan 10 minutes. Turn out.