Heat oven to 300F.
In the bowl of a stand mixer with the paddle beater, mix together all ingredients until clumps form.
Spread the mixtures on a parchment lined (or Silpat lined) sheet pan. Bake for 20 minutes, breaking them up occasionally. The crumbs should be browned and still slightly moist to the touch; they will dry and harden as they cool.
Sprinkle another 1/4 cup crushed graham cracker over the crumble once it is out of the oven.
Let the crumbs cool completely before using in a recipe or eating. Store in an airtight container at room temperature for up to one week. For storage up to one month, store in the refrigerator or the freezer.