Streusel is an essential part of several desserts like pies, muffins, cakes, and pastries. It adds a crunch and sweetness to the dish. However, if you're looking for alternatives to streusel, there are various options available. Crumbles, which are a mix of flour, sugar, and butter, can be used as a substitute for streusel in many recipes. You can also try using oatmeal, brown sugar, or even nuts instead of streusel. Some variations of streusel include almond or hazelnut streusel, which can change the flavor profile of your dish. No matter what substitute you choose, they can all be used to make a delicious and crunchy topping.