Instructions

• Preheat oven to 350°F. Grease and flour two 9×5-inch loaf pans (or line with foil and spray with cooking spray). You can also bake in one 9×5 loaf pan plus about 8 cupcakes instead of two loaves.
• Prepare the red velvet cake batter according to the directions on the 15-ounce box of red velvet cake mix, using the egg, water, and oil called for on the box.
• Divide the prepared cake batter evenly among the pans you are using.
• Make the cheesecake filling: in a stand mixer or with a hand mixer, beat 8 ounces cream cheese and 1/4 cup sour cream (both at room temperature) until smooth.
• Add 1 egg, 1/4 cup granulated sugar, and 1 teaspoon vanilla extract to the cheesecake mixture and mix until combined and mostly smooth (a few small lumps are OK).
• Drop spoonfuls of the cheesecake mixture evenly over the top of the cake batter in each pan.
• Using a butter knife or the back of a wooden spoon, swirl the cheesecake into the cake batter gently to create a marbled effect. Do not over-swirl.
• Bake for 30–40 minutes, or until a toothpick inserted into the center comes out clean. (Note: the cheesecake swirl may settle slightly during baking.)
• Cool the loaves completely in the pans, then remove the loaves from the pans and allow to finish cooling before frosting.
• To make the frosting: beat 4 ounces cream cheese and 4 tablespoons unsalted butter (both at room temperature) until smooth.
• Add 2 cups powdered sugar, 1 cup at a time, mixing after each addition until combined. Add 1/4 teaspoon salt and 2 teaspoons vanilla extract and mix until smooth.
• Refrigerate the frosting until firm enough to spread if needed, then frost the cooled loaves. Store any leftover frosting in the refrigerator.