This copycat Crumbl Celebration Cake Cookie is like a birthday party in cookie form. A fluffy cake batter cookie with cake batter cream cheese frosting and a splash of rainbow sprinkles. Pure joy.
Beat 1 stick unsalted butter and 4 oz softened cream cheese together until light and creamy—this mimics Crumbl's soft, thick texture.
Add granulated sugar, brown sugar, eggs, vanilla extract, and almond extract; mix until just combined so the dough stays tender.
Sift together cake flour, all-purpose flour, cornstarch, baking powder, baking soda, and salt; gradually blend into the wet mixture until a very thick dough forms.
Fold in rainbow sprinkles gently to avoid crushing and discoloration.
Cover dough and chill for at least 60 minutes—chilling is a copycat tip that keeps cookies oversized and prevents excessive spreading.
Scoop dough into 8 large balls (about 145g each), place on parchment-lined pan, and slightly flatten; bake at 350°F (175°C) for 16–18 minutes, until edges are set and centers are just underbaked.
Cool cookies fully on pan—Crumb cookies are soft and thick and will continue to set after coming out of the oven.
Make frosting: Beat 4 oz cream cheese and ½ stick unsalted butter until smooth, add powdered sugar and vanilla extract, beat until fluffy; swirl generously atop cooled cookies.
Finish with extra rainbow sprinkles scattered over the frosting for classic celebration flair.