Preheat the oven to 350 degrees and fill a large muffin tin with cupcake liners.
In a large bowl, whisk together the flour, sugar, and baking powder.
In the mixer, whisk together vegetable oil, milk, eggs, and vanilla.
Gently add in the dry ingredients on low speed until just combined, meaning no pockets of dry ingredients remain in the cupcake batter.
Divide the batter between the prepared cupcake pans. Bake for 16 minutes. Remove the cupcakes to a wire rack and cool completely before frosting.
To make the frosting, add the softened butter to the bowl of a stand mixer fitted with the paddle attachment. Beat on medium speed about 1 minute.
Add the vanilla and mix to combine. With the mixer on low, gradually add the powdered sugar. Turn the mixer to medium high speed and beat until the buttercream becomes light and fluffy - about 2 minutes.
Divide the frosting in thirds and place one third of the icing in a piping bag fitted with a star tip.
Place another third of the frosting in a small bowl and add 2 - 3 drops of bright yellow food coloring. Mix to combine and transfer the frosting to a piping bag.
Add 2 - 3 drops of bright orange food coloring to the last third of frosting and mix to combine. Transfer to a piping bag.
Pipe a small ring of yellow frosting around the top of each cupcake. Then top the yellow with a slightly smaller circle of orange. Finally, top each cupcake with a peak of white frosting to create a triangle shape.
Top each cupcake with a few candy corn if desired.