In a bowl, combine the sugar, flour, cinnamon and butter and mix until it resembles coarse crumbs.

Sprinkle the topping over the muffins or cake and bake until golden brown. Let it set for 25 minutes (if baking muffins) or 30-45 minutes (if baking cake) in the oven.

Remove from oven and let cool on a wire rack for at least 10 minutes.