Two flavors baled in one cake pan is a simple idea. People ask for for multiple flavors in one cake often because of different preferences. Yet once you are faced with the challenge of baking it, well, problems arise.
Of course there is the simple way of baking your say chocolate in one pan, and then your vanilla in another pan and simply pulling the two cakes together. This makes huge sense, especially if you're going with a layer cake you can make chocolate in the first pan and vanilla in the second pan. Once baked, you cut each in half and then layer by flavor, and finally bring the two halves together and DONE.
What happens when you want a single layer half sheet cake, or square cake that you will not be needing a second layer or pan. What then? For years I would fill half my pan on an angle and then add the batter to the other half and what ever happened in the center, happened. Typically a strange marble situation. I don't mind having a specific separation between cakes, but I do not want to me making more cake than needed in order to make multiple flavors. This is how I tackle two flavor cakes baked in one pan.
Of course you want to mix up your multiple flavors, and have them ready to go. You could absolutely use this technique to do more than two flavors in the same plan. For the purpose of this tutorial I will use two, vanilla and chocolate. I will be making them in a 12"x18" half sheet pan.
Grease your pan generously with vegetable shortening, taking care to get the base sides and in the corners.
For the next step, parchment paper or waxed paper work fine. I used wax paper because it is what I had on hand. I prefer parchment for it's versatility, but for baking cakes and not being in direct contact with the heat of the oven wax paper works beautifully.
Tear off a sheet a length longer than the length of your pan by about four inches. Fold the sheet in half.
Then open the sheet and add the edges of the wax paper as if to cover the bottom of your pan, but allow the paper to tepee in the center and fold one way and then the other to create a damn in the center
Now you are ready to begin filling your first flavor. I like to still tilt my pan to keep everything nice and neat.
I just stuck the wax paper box under the one side while I prepared the chocolate batter to go in.
Add the second flavor and take out the lift on the one side. Now that both batters are in, you can now spread it out to the corners it may not have spread to, and make it smooth. I like to add a baker's nail to the chocolate side as close to the center as I can for even baking.
And bake as normal.
As you can see the rise occurred without strange running from side to side. More importantly a nice clean separation line.
After torting, and flipping here is the cake after removing the paper.
And from the center, be careful to pul the cakes apart enough to not ruin your edge.
Finally, you have your two flavors with an even edge. There you have it Two flavors baked in one pan.