In a large mixing bowl, add oil, eggs, whole milk, lime zest, and lime juice. Cream for 2 minutes.
In a large bowl, add sugar, flour, baking powder, baking soda, and salt. Stir into egg mixture and fold.
Spray two 9-inch or three 8-inch cake pans with nonstick cooking spray. Place batter into baking pans. If using three 8-inch pans, bake for 20-26 minutes or until toothpick comes out clean. If using two 9-inch pans, bake for 30-36 minutes. Cool.
To make Lime Cream Cheese Frosting:
In a large bowl, cream together butter and cream cheese for 4-5 minutes until light and fluffy, scraping sides of bowl often. Add powdered sugar, lime juice, lime zest, and cream together. Chill.
Remove cakes from pan. Spread frosting on top of one cooled cake layer. Place the other cooled cake layer on top and spread frosting all over. Garnish with fresh lime slices.