1. Add all ingredients except for butter and vanilla to the bowl of a large food processor. Pulse for about 15 seconds, just to combine. Add the butter and vanilla and process until the mixture resembles a coarse meal – you want it to look much like a boxed mix would.
2. Store the mixture in a zip-top bag in the freezer for up to two months. 

To Make the Cake:

1. Preheat oven to 350°F. Grease and flour the pan of your choice (see recipe yield).
2. Use an electric mixer to beat together the prepared mix, 1 1/4 cups warm water and 2 large eggs until smooth, about 2 minutes.
3. Pour into the prepared pans and bake:

• about 25 minutes for 9-inch layer cakes
• 30-35 minutes for a 13x9-inch cake
• 45 minutes for a bundt cake
• 18-20 minutes for cupcakes.

A toothpick inserted into the center of the cake should come out clean when the cakes are done.