In a medium mixing bowl, cream the softened butter and sugar together with a hand or stand mixer on medium speed until light and fluffy, about 2 minutes. Add in the eggs and mix until just combined.
In a separate bowl, combine all of the dry ingredients and stir them into the wet ingredients. Then fold in the white chocolate chips and sprinkles.
Divide the cookie dough between the baking pans and place on a rack in the middle of the oven.
Bake for 20-30 minutes, depending on the size of pan you use. The middle should still look slightly doughy when you remove it, but be a deep golden brown around the edges. A toothpick inserted should let you know when the cookie is done.
After the cookies have cooled in the pans for about 5 minutes, then turn out on a cooling rack until completely cool.
For The Frosting:
Beat together the butter and powdered sugar and vanilla extract together until fluffy and smooth, about 5 minutes. Add the whipping cream until the frosting is a spreadable consistency.
Use a sharp knife to trim the tops of the cookies to make them even. Stack them together, spreading a generous layer of frosting between each. You can also pipe rosettes on top.
Generously add sprinkles to the top.
And if you’re after the traditional box mix funfetti cake flavor, give clear imitation vanilla extract a try. You can find it at any store that has a cake department with the other flavors.