Preheat oven to 350 degrees F; prepare two 9-inch round cake pans with non-stick cooking spray, or grease with shortening and cover with flour (tapping excess flour out of the pans).
In a medium size bowl, mix flour and baking powder; set aside.
In a large bowl, mix butter and sugar together until light and fluffy using a hand-held electric mixer, or a stand mixer fitted with the whisk attachment.
Beat in eggs, one at a time, and mix until fully incorproated.
Fold 1 1/2 cups of flour mixture in by hand, using a rubber spatula; blend well.
Add milk and vanilla, stirring until thoroughly.
Fold in remaining flour mixture and mix until all ingredients are well blended.
Pour batter into prepared pans and bake for 25-30 minutes or a cake tester inserted into the middle of the cakes comes out clean.
Remove from oven when done and allow to cool for 15 minutes.
While cake is cooling, prepare Jell-o according to instructions on box and set aside.
Randomly poke holes in each cake and pour Jell-o evenly over both cakes.
Place cakes in the refrigerator for approximately 3 hours; remove pans and frost cakes with your favorite cream cheese frosting.