Adapted from Averie Cooks recipe.
What you need:
1 1/2 cup unsalted butter (room temperature)
3/4 cup granulated sugar
1 large egg (room temperature)
1 1/2 tsp vanilla extract
1 1/2 cup all purpose flour (sifted)
2 tsp corn starch
3/4 tsp baking soda
pinch of salt
3/4 cup rainbow jimmies sprinkles
How to make them:
Preheat oven to 350˚F.
Line baking sheets with parchment paper.
In a bowl of an electric mixer, combine the butter, sugar, egg, and vanilla, beat on medium-high speed until light and fluffy about 5 minutes.
In a separate bowl, sift together the flour, cornstarch, baking soda, and salt.
Add the flour mixture into the butter mixture, mix until just combined, scrape down sides as you go.
Add the sprinkles and beat momentarily to incorporate, less then 1 minute or fold in by hand.
Scoop batter onto prepared baking sheets.
Bake for 8 minutes or until edges and tops are set, they should not turn golden or brown.
DO NOT bake more than 9 minutes.
Let cookies cool on sheets for 5 minutes, then transfer to wire rack to continue cooling.