Sheet Cake
"The $22.99 half-sheet that has appeared at every office birthday, graduation, and "we didn't plan this" party since the dawn of Costco."
Costco Copycat — This is a homemade version of the Costco Bakery item. See it in store →
The Game Plan
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Preheat oven to 325°F (160°C). Grease and line a half-sheet pan (18x13) with parchment paper, leaving overhang on the long sides for easy removal.
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Beat softened butter and sugar together until light and fluffy, about 3-4 minutes. Scrape the bowl between additions.
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Add eggs one at a time, beating well after each addition. Mix in vanilla. The batter should be pale and smooth.
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Whisk flour, baking powder, and salt in a separate bowl.
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Alternate adding the flour mixture and milk to the butter mixture in three additions, starting and ending with flour. Mix until just combined — don't overbeat or the cake gets tough.
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Spread batter evenly into the prepared sheet pan. Use an offset spatula to get into the corners. It will seem like a thin layer — that's correct.
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Bake 25-30 minutes until a toothpick inserted in the center comes out clean and the top springs back when gently pressed.
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Cool completely in the pan. Completely. If you frost a warm cake, you get a whipped cream puddle.
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For the frosting: beat cream cheese until smooth with no lumps. In a separate cold bowl, whip heavy cream and powdered sugar to stiff peaks — this takes 3-5 minutes.
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Fold the whipped cream into the cream cheese in three additions, gently, until uniform. Stir in vanilla. Don't deflate it.
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Spread frosting over the completely cooled cake. Go thick — this is not the time for restraint. Use an offset spatula for clean swoops, or just go rustic.
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Refrigerate at least 1 hour before slicing. Decorate with sprinkles, fruit, or a hastily written "Happy Birthday" if the occasion calls for it.
