Combine the flour, sugar, and salt in a food processor. Add the butter and pulse until the mixture begins to form a crumbly, curdy—not cohesive—dough. Process more for big clumps and less for a pebbly, sandy texture. (You can also do this step in a bowl with your hands!)
Dump onto a plate and continue to squeeze and break-apart the mixture until it looks right to you. (Streusel is very personal. Don’t let anyone tell you otherwise!) Refrigerate for a few hours or freeze for 30-ish minutes until firm. (This will reinforce the streusel’s crumby personality.) Bag and store in the fridge for up to five days or in the freezer for up to 2 months.
To make streusel crunch, heat the oven to 325° F and line a baking sheet with parchment or a silicone mat. Spread into a single layer (you may need to use 2 sheets if you can't spread the streusel out adequately) and bake until the streusel begins to brown and crisp—about 20 minutes total, tossing with a fork halfway through. It will continue to crisp as it cools. Cool completely before sprinkling on everything from soups to pastas. Store in an airtight bag or jar for up to 3 days.
Emma is a writer and recipe developer at Food52. Before this, she worked a lot of odd jobs, all at the same time. Think: stir-frying noodles "on the fly," baking dozens of pastries at 3 a.m., reviewing restaurants, and writing stories about everything from how to use leftover mashed potatoes to the history of pies in North Carolina. Now, she lives in Maplewood, New Jersey with her husband and their cat, Butter.