Preheat the oven to 350 degrees F. Add cupcake liners to the muffin pan.
In a medium sized bowl add the following ingredients: all-purpose flour, cake flour, kosher salt, baking soda, and baking powder. Mix well and set aside.
Using an electric mixer, on medium-low speed add unsalted butter and sugar. Mix for 3 minutes.
Add the egg and continue to mix on medium-low speed, until the egg is fully incorporated 1-2 minutes.
Next, alternate between adding the flour mixture, milk, and Greek yogurt to the electric mixer. Once all ingredients are mixed well, turn off the mixer.
Fold in the sprinkles. Fill the cupcake liners 3/4 full with cake batter. Bake for 18 minutes or until toothpick inserted comes out clean.
Allow the cupcakes to cool completely on a cooling rack before frosting.