Homemade Make-Ahead Yellow Cake Mix
*Update (6/28/10): When I originally made this cake, it baked up just fine in a 9X13-inch pan. However, when I went to use the same recipe for one of the Wilton cake pans (Spiderman, to be exact), there was way, way too much cake batter. The instructions on the Wilton pan said to use one recipe boxed cake mix. This homemade version is supposed to be the equivalent of one boxed mix; however, I'm realizing that the homemade version gives you more cake than what a boxed version does. So what I ended up doing for the Spiderman cake is taking out batter from the pan before I baked it (since I knew it was going to overflow in the oven). I had enough leftover batter for 8 cupcakes (filling them about 2/3 full). If you plan on making this cake in a 9X13-inch, bundt or 9-inch rounds, I would recommend taking out some of the batter, especially since some commenters have indicated the cake has baked up unevenly (burnt edges, gooey middle). It seems like the batter needs to be downsized in order for the cake to bake evenly. I will continue to test the recipe and scale it back as needed (including weighing the dry ingredients next time to compare with the weight of a boxed mix), but until "then" take this note into consideration. Cupcakes will still work great - you'll probably get more like 30+ cupcakes out of the batch. Incidentally, I love the flavor and taste of this cake enough to keep baking it, despite the annoyances of batter.
*Note: the recipe calls for cake flour, which I never have on hand so I substituted 2 3/4 cups plus 1 tablespoon all-purpose flour and 3 tablespoons cornstarch for the three cups of flour called for in the recipe. It worked beautifully.
*Makes enough for two 9-inch layer cakes (bake according to recipe), or one 9X13-inch cake (bake for 35 to 40 minutes), or one 12-cup bundt pan (bake for 40 to 45 minutes), or 24 cupcakes (bake for 18 to 20 minutes)
2 cups granulated sugar
1 1/2 cups all-purpose flour
1 1/2 cups cake flour
1/2 cup nonfat dry milk powder
1 tablespoon baking powder
1 teaspoon salt
16 tablespoons butter (2 sticks), cut into 1/2-inch pieces and chilled
1 tablespoon vanilla extract
Process sugar, flours (or flour and cornstarch if making the substitution for the cake flour), milk powder, baking powder, and salt in a food processor for 15 seconds to combine. Add butter and vanilla and pulse until the mixture resembles coarse meal (you want this much finer than, say, a pie crust). Freeze the dry mixture in a zipper-lock bag for up to 2 months or use immediately.
To make the cake, adjust an oven rack to the middle position and preheat the oven to 350 degrees. Grease and flour your pan of choice (see the note above the recipe).
With an electric mixer, beat the prepared cake mix, 1 1/4 cups warm water and 2 large room-temperature eggs until the mixture is smooth, about 2 minutes. Scrape the batter into the prepared cake pan(s) and bake until a toothpick inserted in the center comes out clean, about 25-27 minutes for two 9-inch layer cakes. See the note above the recipe for alternate cooking times with other baking pans. Cool the cake(s) in pan(s) for 10 minutes, then turn out onto a wire rack. Cool completely.