Preheat the oven to 350°F (177ºC). Prepare three 6-inch or two 8-inch cake pans by spraying the sides with baking spray and lining the bottom with a parchment paper circle. Alternatively, you can grease and lightly flour the pans.
In a medium bowl, add the sifted cake flour, baking powder, baking soda, and salt. Whisk to combine and set aside.
In the bowl of your stand mixer fitted with the paddle attachment (or a handheld mixer with a large bowl), beat the butter on high for two minutes until it’s creamy. Add in the white and brown sugars and continue to mix on medium-high for another two minutes, scraping down the bowl and paddle as needed. Turn the mixer to low speed and add the eggs one at a time. Add the vanilla and sour cream, turn the mixer to high, and mix for one minute, scraping down the bowl and paddle once more.
With the mixer on low speed, add in the dry ingredients and mix until just combined. Add the whole milk and mix until just incorporated. Scrape down the sides and bottom of the bowl and give it a few stirs to make sure there are no lumps.
Coat the mini chocolate chips in 2 teaspoons of flour, then gently fold them into the batter using a rubber spatula.
Pour batter evenly between the prepared cake pans (about 2/3 of the way full) and bake for 30-35 minutes, until a toothpick inserted into the middle comes out clean or with a few moist crumbs. Let the cakes cool in the pan for five minutes before turning them out onto a wire rack for an additional few hours of cooling. Make sure they’re entirely room temperature before applying any frosting.