Internal Temps of Crumb/Streusel Cakes

Hi All,

I'm an experienced baker, and 95% of the time I can tell when my coffee cakes/crumb muffins are done. But 5% of the time (especially with a new recipe) I get an under-bake. If I use the toothpick method, that crumb topping scrapes the toothpick clean and it becomes somewhat of a guessing game.

I have a thermopen, and I would like some advice on the internal temp I should be looking for as far as doneness in degrees, either ºF or ºC works for me. Thanks!