• Preheat your oven to 350°F and line a 12-count muffin pan with cupcake liners. Lightly spray the inside with non-stick cooking spray.
• In a medium bowl, sift together the flour, baking powder, baking soda, and salt.
• In a separate bowl, whisk together the oil, sugar, room temperature eggs, vanilla, sour cream, and milk. Carefully add the dry ingredients to the wet ingredients and whisk until just combined and no more flour pockets remain.
• Pour the batter evenly into the cupcake liners. Gently tap the pan on the counter to get rid of any air pockets.
• Bake in the preheated oven for 15 minutes. A toothpick inserted in the center should come out clean.
• Let the cupcakes cool completely in the fridge before frosting.

Vanilla buttercream frosting:

• Use a hand-held or stand mixer fitted with a paddle attachment, starting on the lowest speed, beat the softened unsalted butter, powdered sugar, vanilla extract, heavy cream, and salt until smooth and creamy. Scrape down the sides of the bowl as needed. If the frosting is too thin you can add more powdered sugar as needed, or if it's too thick you can add more cream.
• Keep frosting out at room temperature until ready to pipe onto the cupcakes.