Two delicious desserts collide in this sweet, colorful cookie cake! Just like a cookie, the center is chewy, and just like a cake, you can slice this to serve a crowd.
Preheat oven to 350°F. Line a 9-inch pie dish with parchment paper.
Mix the wet ingredients. In a large bowl using a hand mixer on medium speed, cream the butter and sugar until light and fluffy, about 1 minute. Beat in the egg and vanilla.
Mix the dry ingredients. In a separate large bowl, whisk together the flour, salt, baking powder, baking soda, and cream of tartar.
Combine the ingredients. Slowly add the dry ingredients to the wet ingredients, stirring to combine using a rubber spatula. The dough will be thick, like cookie dough. Use the spatula to gently fold in the white chocolate chips and sprinkles.
Bake the cookie cake. Press the cookie dough evenly into the prepared pan. Bake for 25 to 30 minutes. The center will still be slightly soft when done, but the edges and top will turn a light golden brown. Do not wait until the center is firm, or you will overbake the cookie cake. Lift the cake out of the pie dish by gripping the parchment paper, then transfer to a cooling rack. Allow the cake to cool completely before slicing into it.
Notes
Makes approximately 8-10 servings.My original recipe can be found in Chapter 4, page 79-80 of my second cookbook, The Super Easy Teen Baking Cookbook (Rockridge Press, 2021).