Preheat the oven to350 degrees. Grease and flour 3 - 9 inch round baking pans. (This recipe makes a 3 layer cake.)
Mix together the flour, baking powder, and salt. Set aside.
Using a standing mixer, or electric hand mixer, beat the butter until smooth. Then add the oil, sugar, and vanilla, beating until combined. Add the eggs, one at a time. Beating again until smooth. Then add about half of the flour mixture and a cup of milk. Beat this on low speed. Then add the rest of the flour mixture and the last cup of milk, beating until just combined. Gently stir in the sprinkles. Do not over mix or colors from sprinkles tend to bleed into the batter.
Divide the cake batter evenly into the prepared pans. Bake the cakes for 30 minutes. Remove the cakes and place on cooling racks. Let them sit for 10 minutes.
Carefully remove the cakes from the pans and allow them to cool completely. While the cakes are cooling you could prepare your frosting.
To assemble the cake, you may need to slice off the rounded tops of the cake layers to make them flat for layering. Then put one cake layer on your serving dish. Cover it with frosting. Add a second layer and cover it with frosting. Add the third layer and cover it with frosting. Then be sure to frost all around the edges, right down to the bottom to seal the cake and keep it moist.