Our easy crumb topping -- a blend of butter, flour, light-brown sugar, salt, and cinnamon -- makes any muffin, no matter how simple, seem special. This recipe can also be used to make our Blueberry Crumb Cake.
In a medium bowl, whisk together flour, brown sugar, cinnamon, and salt. Add butter, and mix together with your hands or a pastry blender until well combined but still crumbly. (Alternatively, you can use an electric mixer.)
Topping can be stored in an airtight container in the refrigerator for up to one week or in the freezer for up to one month; before using frozen topping, thaw completely at room temperature.