Baking square cakes is just a little bit trickier than baking round cakes. Square cake pans distribute the heat a little differently, letting the center of the cake rise faster than the corners. This can make it hard to bake square cakes and then stack them in layers unless you cut the tops off, which makes frosting them harder. Understanding and compensating for the nuances of square cake pans goes a long way toward ensuring that your square cakes come out perfectly every time.
Preheat your oven to the temperature recommended by your recipe or cake mix. If the instructions are for a round cake or they do not adjust for shiny aluminum pans, lower the suggested temperature by 25 degrees Fahrenheit. This will keep the top of the cake from rising faster than the corners, and will also keep the cake from overcooking.
Grease your square pan with vegetable shortening. Use your fingers or a pastry brush to cover every inch.
Sprinkle barely enough flour into the greased pan to cover the bottom. Shake and tap the sides of the pan as you turn it to encourage the flour to coat the bottom and all four sides. Make sure you coat the corners well. If you are baking a chocolate cake, use powdered cocoa instead of flour. Shake out and discard any excess.
Prepare your cake batter according to the recipe or mix. If you are adding fruits or nuts, dredge them with flour first. This will help keep them suspended in the cake batter while it cooks.
Pour the cake batter into the square pan. Even out the top of the batter and push batter into the corners of the pan with a spatula.
Bake the cake in the center of the oven, for the time suggested. Insert a toothpick into the center of the cake when the time is up. The cake is done if the toothpick is clean when you pull it back out of the cake.
Set the square pan on a cooling rack for at least 10 minutes or until the cake pan is cool enough to handle.
Slide the blade of a butter knife carefully between the side of the cake and the inside of the cake pan. Be very careful when dealing with the corners.
Take the cake pan off of the cooling rack. Place two to three layers of paper towels on top of the cake.
Flip the cooling rack over and place it on top of the paper towels. Hold the rack with your fingers and slide your thumbs under the cake pan. Flip the cake pan and rack and set the rack on the counter.
Ease the pan off of the cake. The paper towels will keep the cake from breaking and falling through the wires on the rack.