Dorie says toss all the dry ingredients in a bowl, and drop in the chopped butter. Reach in with your hands and start rubbing and squeezing the ingredients together until you’ve got a rocky road mix and you no longer see butter. Cover and chill the streusel mixture for at least two hours, or up to two days.
Center a rack in a preheated oven to 350 degrees. Line a baking sheet with parchment paper. Turn the crumbs onto the baking sheet and, using your fingers, rub the streusel so you don’t have too many large lumps.
Bake 15 to 18 minutes, mixing, turning, and stirring the streusel twice, until the crumbs separate into small grains. The crumbs will look sandy, and you’ll have a few pebbly pieces here and there. Let the crumbs cool; they’ll become crisp.
Dorie says she keeps her crumbs in an air-tight container on the kitchen counter, or they can be refrigerated or frozen. The point is to have fun putting them on anything and everything that sounds good. I’m thinking of oatmeal, dressed up with buttery chocolate crumbs and, why not, an added sprinkle of toasted coconut. That’s a reason to get up in the morning.