1 cup (2 sticks) unsalted butter, at room temperature
1¾ cups granulated white sugar
2½ cups cake flour
1¼ teaspoons salt
2 large eggs
1 cup buttermilk
1 teaspoon vanilla extract
1 teaspoon baking soda
1½ teaspoons white vinegar
1½ teaspoons unsweetened cocoa powder
2 ounces red food coloring
2 cups powdered sugar
1/2 cup (4 ounces) cream cheese, at room temperature
1/8 to 1/4 teaspoon ground cinnamon (optional)
1 to 2 tablespoons milk, as needed- to thin-out
PREPARE THE CAKE:
Preheat the oven to 350 degrees F. Spray a bundt cake pan generously with cooking spray; then dust lightly with flour.
In a large bowl, use an electric mixer to combine the butter and sugar; set aside. Sift together flour and salt; set aside. In a separate bowl, whisk together the eggs, buttermilk, vanilla, baking soda and vinegar. Alternate adding the flour mixture and buttermilk mixture to the butter mixture. Mix well after each addition.
In a small bowl, mix the red food coloring and cocoa powder; add to the cake batter and mix just until combined.
Pour the batter into the prepared bundt pan and bake for 35 to 45 minutes, or until a toothpick comes out clean. The baking time will vary based on the size of your pan. Allow to cool for about 30 minutes before turning the bundt pan over onto a rack to remove from the pan. Let cool completely before adding the glaze.
PREPARE THE GLAZE:
When you're ready to add the glaze, use a large spatula or flat cookie sheet to slide under the cake and move it to a platter. Use an electric mixer to blend together the glaze ingredients. Add just enough milk to make the glaze thin enough so that it will drip down the sides of the cake, but not so thin that it will drip off of the cake. If you accidentally get it too thin, just add more powdered sugar. Spoon the glaze onto the top of the cake and let it ooze down the sides. Refrigerate until ready to serve.