For a crisp that serves six to eight, a good place to start is with 1/2 cup (1 stick) of butter: then add equal parts light brown sugar (1/2 cup) and two parts flour (1 cup). **Note: I sub almond meal, quinoa flour, oats, etc... for flour.
Add a generous pinch of salt, and a pinch of cinnamon and/or nutmeg. If you want to add rolled oats or slivered almonds, mix these in now, too—you can add just a little, or up to as much as the amount of butter used.