Cake

1. Preheat the oven to 350F/180C and heavily grease two 8-inch cake pans or two 9-inch cake pans, and set them aside. Your oven must be properly preheated for your cake to bake properly
2. In a medium bowl combine the cake flour, baking powder, baking soda, and salt. Set aside.
3. In a bowl of an electric mixer fitted with a paddle attachment or a large bowl with a handheld electric mixer on medium speed combine the butter and sugar for 4-5 minutes, so it's nice and fluffy. Mix in the oil until fully combined. Add in the vanilla extract and one egg and mix to combine. Scrape down the sides of the bowl and mix in the other egg.
4. In a small bowl mix sour cream and buttermilk.
5. To the butter mixture add 1/3 of the dry ingredients, mixing until just combined, then 1/2 of the wet ingredients, then repeat with the remaining ingredients ending with the dry ingredients. Then gently fold in the mini chocolate chips.
6. Divide the batter evenly between the two prepared pans and spread it into an even layer. Bake for 25-30 minutes, the 8-inch cake pans will take a bit longer to cook than the 9-inch cake pans. You can insert a toothpick inserted into the center of the cake to check for any wet batter OR gently press the top of the cake and it should bounce back immediately. Transfer the cake pans to a wire rack to cool for 20 minutes then invert out of the pan to cool completely before frosting,

Frosting

1. In the bowl of an electric stand mixer beat the softened cream cheese and butter for 2 to 3 minutes on medium to high speed. You can also do this in a large bowl with a handheld mixer. The mixture should be light and fluffy.
2. While the cream cheese is beating sift the powdered sugar into another clean bowl. This helps prevent a lumpy frosting.
3. When the butter and cream cheese mixture is ready 1/2 of the powdered sugar. Mix low at first to prevent a powdered sugar storm in your kitchen, then increase the speed to medium-high and beat for 3 minutes. Turn the mixer off and add the remaining powdered sugar mixing again for another two minutes. Scrape down the sides of the bowl and add the salt, heavy cream, and vanilla extract. Mix again for 2 minutes.
4. Gently fold in the mini chocolate chips. Then add two large scoops to the top of one of the cake layers and spread into an even layer. Then place the second cake on top and spread the remaining frosting to cover the cake. Garnish with more mini chocolate chips if desired. Store the cake in a covered container in the refrigerator for up to three days, I suggest letting the cake sit at room temperature for 30 minutes before serving. If making an American buttercream frosting the cake can be stored at room temperature.