- 1 1/2 cups unsalted butter, at room temperature
- 3 cups sugar
- 5 eggs, separated
- 3 cups all-purpose flour
- 3/4 cup lemon lime soda
- 3 teaspoons lemon juice
Preheat the oven to 325 degrees F.
In a standing mixer fitted with the paddle attachment, cream the butter until fluffy. Slowly add 2 cups of the sugar and mix until just incorporated. Raise the speed to high and mix until light and fluffy. Add the egg yolks, 1 at a time, until incorporated.
Reduce the mixers speed to low. Alternately add the flour and soda until a smooth batter is formed. Transfer the batter to a large bowl.
Clean the bowl of the mixer and place the egg whites inside. Using the whisk attachment, whip the egg whites until foamy. Add the lemon juice and beat until soft peaks are formed. Add the remaining sugar and beat until stiff peaks are formed.
Working in 3 batches, using a rubber spatula, fold the egg whites into the batter.
Pour the batter into the pan and bake until golden brown and a toothpick inserted in the center comes out clean, about 50 minutes to 1 hour. Allow to cool completely about 2 hours, then unmold and serve.