Preheat oven to 350°F and line cupcake pans
Cream butter, sugar, and oil until light and fluffy
Add eggs one at a time, then mix in vanilla
Combine flour, baking powder, and salt in a separate bowl
Alternate adding dry ingredients and milk into batter
Fill liners two-thirds full and bake for 18 minutes
Cool cupcakes completely before frosting
Prepare buttercream by mixing butter and powdered sugar
Divide frosting and color half blue
Spread white frosting on half of each cupcake
Spread blue frosting on the other half
Top white side with crushed graham crackers
Add sprinkles and decorate with candy shells