Before baking your cake batter, you will have to do a bit of prep on your pans. Pouring the batter into an unprepared pan will cause it to stick to the sides and tear itself apart as the temperature rapidly changes. Bakers use a simple technique to combat this called "butter and flour," which involves—you guessed it—applying butter and flour to the pan. It's quite a simple step and will make your cakes retain a perfect shape every time.
So that I always have sotfened butter available when needed, I keep salted butter outside of the refrigerator in a butter bell.
Get your pan ready. If your pan has a fixed bottom (unlike springform pans which have a detachable bottom), then you will want to also cut out a piece of parchment paper to fit the bottom. Butter and flour alone will only work for the sides. Both parchment and the butter-flour combo are necessary on the bottom so the cake falls right out of the pan with ease.
You will probably get some sticking, but only a minor cling. Simply use a knife to trim around the edge that still sticks to the pan. Now you're well-equipped to tackle a sponge cake recipe.
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