Preheat the oven to 325°F.
Grease a bundt pan very well and lightly flour. Set aside. In a large mixing bowl combine flour, cake flour, baking powder, baking soda and salt. Set aside.
2 cups all purpose flour, 2/3 cup cake flour, 1 1/2 teaspoons baking powder, 1 teaspoon baking soda, 1 teaspoon salt
In the bowl of a stand mixer fitted with a paddle attachment add the sugar and butter. Beat on medium speed, until light and fluffy, about 5 minutes. 1 3/4 cups sugar, 1 cup salted butter
Add the eggs and egg yolks and mix to combine.
4 eggs, 3 egg yolks
Next, add in the sour cream and mix until well incorporated.
1/2 cup sour cream
Add in milk, vinegar, vanilla extract and red food coloring and mix until combined.
1 1/2 cups milk, 3 tablespoons white vinegar, 2 1/2 teaspoons vanilla extract, red food coloring
Gradually add in the flour mixture and pudding mix while mixing on low speed.
3.4 ounce package vanilla instant pudding mix
Add in cocoa powder and mix until just combined.
1/3 cup unsweetened cocoa powder
Add in more red food coloring, if needed.
Transfer the batter into the prepared bundt pan, then place into the preheated oven on the center rack.
Bake for 1 hour and 10 minutes or until a toothpick inserted into the center comes out clean or with just a few moist crumbs.
Once baked, remove from the oven and place onto a wire cooling rack to cool for 10 minutes. Once the cake has cooled down, place a cooling rack onto the opening and carefully flip over to release the cake. Let the cake completely cool before frosting. Prepare the frosting as the cake cools.
In the bowl of a stand mixer fitted with a paddle attachment combine powdered sugar, cream cheese, butter, vanilla extract and salt.
1 1/4 cups powdered sugar, 8 ounces cream cheese, 1/2 cup salted butter, 1 teaspoon vanilla extract, 1/4 teaspoon salt
Mix together on low speed until the powdered sugar is incorporated, then turn the mixer speed up to medium-high and beat until fluffy and creamy.
Once the cake is completely cooled, transfer it to a plate or a cake stand. Spoon the frosting into a piping bag fitted with a round tip. Pipe lines onto the cake. You can use the crevices from the bundt pan to use as a guide or pipe however you wish. Cut into 12 slices and serve.