Fudgy Cream Cheese Ribbon Cake

This is the recipe I was going to bring to the swap, but I had a baby instead. :)

1 (18 1/2 ounce) box chocolate cake mix
1 (3 1/2 ounce) box instant chocolate pudding mix
8 ounces cream cheese, softened
2 tablespoons butter, softened
1 tablespoon cornstarch
1 (14 ounce) can sweetened condensed milk
1 egg
1 teaspoon vanilla

Preheat oven to 350º. Grease and flour, (may use baking cocoa instead), 10” bundt cake pan WELL. Prepare cake mix according to package directions. Adding dry instant pudding mix. Pour batter into pan. Set aside. In mixing bowl, beat cream cheese, butter and cornstarch until fluffy. Slowly beat in sweetened condensed milk. Beat in egg and vanilla, beating til smooth. Spoon evenly over cake batter. Bake 50-55 minutes til toothpick comes out clean. Cool 10-15 minutes; CAREFULLY remove from pan onto cake plate. You may have to tap sides quite a bit to loosen or run a knife around edge to help loosen. Sprinkle with powdered sugar or drizzle with white chocolate and/or chocolate glazes if desired.