In a large food processor, mix together dry ingredients until well-blended.
Add butter and vanilla and pulse until mixture resembles coarse crumbs.
Divide mixture in half (about 3 1/2 cups) and pour into two large Mason jars or freezer bags.
Store in the freezer for up to 2 months.
To make the cake
1 jar cake mix
1 1/4 cup warm water
2 large eggs
Preheat oven to 350°F. Grease two 8-inch cake pans and line the bottom with parchment paper.
Beat mix, water, and eggs together until few lumps remain. Divide between cake pans.
Bake for about 25 minutes, until a toothpick inserted in the center comes out clean.