¼cup(57g) unsalted buttercold and cut into small pieces3
Place flour, brown sugar, cinnamon, and salt into a small bowl. Toss together with a fork until combined.
Add the butter to the bowl, then use a fork to smash the pieces of butter into the mixture.
Use your fingers to press the ingredients together until butter is in small chunks. I like to pick up chunks of butter and gently pinch them between my thumb and pointer and middle fingers to flatten slightly. I then drop the flattened pieces of butter back into the mixture so they pick up the dry mixture, then go through the whole bowl again with all of my fingers to "fluff" the mixture and turn the flattened pieces back into larger chunks. You are aiming for mostly medium-size chunks and some smaller and larger chunks.
To use: scatter evenly over muffins, breads, cakes, and pies before baking. As written, this streusel recipe will top about 18 standard size muffins. Halve the recipe for a quick bread in a standard size loaf pan or a streusel layer in the middle of a bundt pan cake.
To make ahead: you can make this streusel up to 3 days in advance. Store covered tightly in the refrigerator.
To add oats or nuts: to make this streusel topping with oats or finely chopped nuts, add ½ cup along with the dry ingredients. The instructions are the same.
Brown sugar: I like to use all brown sugar, but you could use all granulated (white) sugar or half brown and half granulated. Granulated sugar will bring a little more texture to your streusel. The instructions and method are the same.
Salt: I use table salt. If you use a larger, flakier, or coarser salt, you may want to increase this to ½ teaspoon. If you are using salted butter, decrease the added salt to just ⅛ teaspoon.
Butter: I typically cut my ¼ cup of butter into 16 pieces. Cut the stick in half long ways, turn it on its side and cut in half long ways again, then slice into 4 slices. This will make 16 small pieces. You can also use salted butter. Decrease the added salt to just ⅛ teaspoon.