I have to say that when I read the list of ingredients and saw MAYONNAISE amongst the list, I was a tad put off. The blog I got the recipe from claims the mayo is supposed to make the crumb topping more crisp. I have to admit... I think they were right!
In a large bowl, stir together the flour, the sugars, and the cinnamon.
Stir in the mayonnaise until the mixture looks almost like dough.
Crumble the mixture over the fruit.
Bake for 35-40 minutes, until the top is lightly browned.
Serve with a dollop of homemade whipped cream! ENJOY!