Preheat oven to 325 Degrees F. Line 24 + standard cupcake tins with cupcake liners. (Makes a little more than 24 cupcakes)
In the bowl of a stand mixer using the paddle attachment cream together oil and sugar for 3 minutes until fluffy. Add eggs on at a time mixing well between each addition and scraping the sides of the bowl. Add the vanilla and mix well.
In a separate bowl sift together the flour,baking powder and salt.
Gradually add the dry ingredients to the wet. Scrape sides of the bowl and mix on low for about 1 minute.
Add the sour cream and mix just enough to incorporate, about 30 seconds.
Add Sprinkles and fold into batter to incorporate. Careful not to over mix or you run the risk of the colors running into the batter.
Fill each cupcake liner with about 1/4 cup of batter and bake for 18-20 minutes.
Cool completely and frost with Buttercream Frosting.
For the Buttercream Frosting
In a 5 or 6 Quart Bowl of a stand mixer cream butter and shortening on high speed for 3-5 minutes until smooth and pale yellow in color.
While butter and shortening are mixing measure out your cream and milk. Add your vanilla extract to milk and cream. Set aside.
Add 1 pound of confectioner sugar to your mixing bowl with butter and shortening. Top with milk mixture. **(Drape a clean dish towel over the mixer and hold down against the sides of the bowl. Otherwise you'll have a white cloud of sugar everywhere!) Turn mixer on low for 1 minute. Once sugar is mixed in remove towel and scrape sides of mixer then turn mixer on medium speed and mix for 2 to 3 minutes. Scrape sides of bowl then mix on high for 1 minute.