Preheat the oven to 350 degrees F. Place cupcake liners into your cupcake pan(s).
In a medium bowl, whisk the cake flour, baking powder, baking soda and salt for 30 seconds. Set aside
In another bowl, add the buttermilk and vanilla extract. Set aside.
In the bowl of your mixer, add the butter and mix at medium speed until smooth. Gradually add the sugar and continue to mix on medium speed for 3 to 5 minutes until lightened in color and fluffy. Add the eggs one at a time mixing after each addition until the yellow of the yolk is well blended.
With the mixer on low speed, alternately add the flour mixture and buttermilk mixture, beginning and ending with the dry ingredients. (3 additions of dry ingredients and 2 of liquid). After the last addition, mix just until combined. Be careful not to over-mix.
Fold in the ½ cup of multi-colored jimmies. (You can add a bit more if you'd like, we were happy with the amount of color from the ½ cup.)
Scoop about ¼ cup of batter into each of the lined wells of the cupcake pan.
Bake at 350 degrees for 15-18 minutes or until a toothpick inserted in the center comes out clean or with just few crumbs attached. We like to remove the cupcakes immediately from the pan to prevent over baking. Allow to cool on a wire rack.