I've made this recipe twice in the last two weeks. It is one of those recipes that is great because I would almost always have all of the ingredients on hand. I guess the problem would be that, while they are good muffins, they aren't my favorite muffins ever.
The crumb gave me some trouble the first time. It basically melted off all over the muffin tins and burned. The second time, I reduced the amount of butter by a tablespoon and that corrected the problem.
Here is the muffins pre-cooked and fully topped with crumb:
Completely covered, right? Then why did I have this much crumb left over?
Here's the finished muffin - a quick picture before I left for work this morning: