Add sour cream, milk and mix until completely combined. Scrape the sides and bottom of the bowl with a spatula and stir again to ensure the batter is uniform.
Divide into prepared 8” pans, and bake on 350F for 32-35 minutes or until the top springs back when lightly touched and a, toothpick inserted in center comes out clean.
These cakes typically bake up with a dome so I recommend leveling with a cake leveler (linked in equipment section on site) or serrated knife before decorating.