It's not something I do either Anneke. I just had the idea while reading the last few posts on this thread. I'm not sure what you would like your topping to contain, i.e. nuts, oatmeal, etc... I checked a few books and found the following recipes.
3/4 cup all purpose flour
1/3 cup sugar
1/3 cup brown sugar, packed
1/4 teaspoon cinnamon
1/2 cup very cold butter, cut into 1/2 inch pieces.
Combine all the dry ingredients in the bowl of a food processor fitted with the metal blade. Add the butter and pulse several times until the mixture is a crumbly consistency. Be careful not to over mix or the topping will become doughlike. Refrigerate for up to 1 week or freeze for up to one month. It's a filling for a multifruit Danish ring. Makes 2 cups.
From The Village Baker's Wife by Gayle and Joe Ortiz
I just found a recipe for a pear crisp in a skillet. It might be perfect for your idea. The fruits are cooked on top of the stove then the topping is added and it bakes for about 20 in a 400°F oven. I'll just type the topping recipe for now but if you want the whole recipe just let me know.
1/2 cup pecans
1 tablespoon plus 1 teaspoon light brown sugar, lightly packed
1 tablespoon plus 1 teaspoon sugar
1/2 teaspoon kosher salt
1/2 teaspoon baking powder
1/2 teaspoon cinnamon
3/4 cup unbleached pastry flour or unbleached all purpose flour
3 1/2 tablespoons unsalted butter, cut into 1 inch cubes and frozen
1/2 extra large egg, beaten equal to 2 tablespoons
In the bowl of a food processor fitted with the metal blade, grind the pecans and sugars to a fine meal. Add the salt, baking powder, cinnamon and flour and process to combine. Add the butter and pulse on and off until it is the consistency of coarse meal. Transfer to a bowl. Add the measured egg and toss together to incorporate. Chill until ready to use.
From Pastries From La Brea Bakery by Nancy Silverton
1 1/3 cups all purpose flour
2 1/2 teaspoons cinnamon
2/3 cup sugar
1 teaspoon vanilla extract
11 tablespoons cold unsalted butter, thinly sliced
In a food processor, combine the flour, cinnamon and sugar. Add the vanilla and pulse to mix. Add the butter, a few pieces at a time, and pulse until the mixture crumbles into pieces about twice the size of peas. Refrigerate or freeze the streusel if not using immediately. It's a topping for crumb buns to be bake at 350°F for 30 to 35 minutes.
From: Classic Home Desserts by Richard Sax
When I get a little money, I buy books. And if there is any left over, I buy food.
- Desiderius Erasmus