2 cups chopped walnuts, roasted
3 cups packed brown sugar
1/2 cup unbleached all purpose flour
2-3 tablespoons cinnamon
1/2 teaspoon fresh nutmeg (optional)
1/4 teaspoon salt
1 tablespoon vanilla
1 cup very cold, unsalted butter - cut into 16 chunks
Combine walnuts, brown sugar, flour, cinnamon, nutmeg, salt, and vanilla in a food processor and Pulse briefly- just enough to combine. Add butter chunks and pulse again, until the mixture becomes coarse & crumbly.
Freeze in Ziploc or vacuum seal bags. To use add as liberally as desired to the top of muffin batter, quick bread batter, prepared apples, blueberries or peaches (to make fruit crisp) and bake as directed in the recipe you're using.