There's also this "struessel" topping, which isn't really struessel, but is SOOOO tasty and gives it that bakery touch. It's a mix of flour, butter and sugar. I would like to try brown sugar next time:
Then guess what I forgot to do? Take pictures of the finished product! So, I thought I'd provide the link to the recipe since I forgot those pictures. They lasted about 2 seconds in my house. If you want to be healthier, just replace oil with applesauce.
I filled my muffin cups very full so that the tops were really large and overflowing. But make sure if you do this to get plenty of oil on the top of your pan too.