1 ¾cupscake flour, (see note for easy substitution)
1 ¼cupsall-purpose flour
1 ¾cupsgranulated sugar
2 ½teaspoonsbaking powder
1teaspoonsalt
1cupunsalted butter, (2 sticks, room temperature)
4eggs, room temperature
1cupwhole milk
2teaspoonsvanilla extract
½cuprainbow sprinkles, (jimmies)
For the Vanilla Buttercream:
1cupunsalted butter, (2 sticks softened, not melted)
3-4powdered sugar, sifted
¼teaspoonsalt
1tablespoonvanilla extract
Up to 4 tablespoons heavy cream, half and half, or milk
Instructions
For the Cupcakes: Bring the unsalted butter and eggs to room temperature; combine the milk and vanilla in a liquid measuring cup. Preheat the oven to 350 degrees F. Prepare cupcake pan with 24 liners.
In a mixing bowl with the paddle attachment, add the flours, sugar, baking powder, and salt; mix on low-speed for 1 minute. Then add the butter a little at a time keeping on low-speed. It will begin to look like coarse sand.
Continuing on low-speed add the eggs one at a time. Very slowly, a few tablespoons at a time, add in the milk and vanilla. Increase the speed of the mixer to medium and beat for 2 minutes, until batter is smooth. Remove the bowl from the mixer and using a rubber spatula, gently fold in the sprinkles.
Fill the liners two-thirds full and bake for 15-20 minutes, or until an inserted toothpick comes out clean. Do not overbake! Cool in the pan for 10 minutes and remove to cool completely on a wire rack.
For the Frosting: In a mixer, using the paddle attachment, beat the butter on medium speed.
Turn off the mixer and add 3 cups of the sifted powdered sugar and mix until the sugar is incorporated. It will look clumpy!
On medium speed, add the vanilla extract, salt, and 2 tablespoons of the heavy cream and beat for 2-3 minutes, until it is whipped, fluffy, and creamy.
If your frosting needs more stiffness (or you like it a little sweeter), add more sifted powdered sugar, a little at a time. If it needs to be thinned out, add remaining heavy cream, 1 tablespoon at a time.
Frost cooled cupcakes and add additional sprinkles on top. I used a Wilton 2D tip for these cupcakes.
Notes
Cake Flour Substitute: 1 cup cake flour= 1 cup all-purpose flour, minus 2 tablespoons, and 2 tablespoons cornstarch; sifted 5 times together to incorporate and lighten the flour. Use unsalted butter to be able to adjust the desired flavor. When the butter is at room temperature, it will feel like soft-serve ice cream.Source: my friend and chef Louise Rio