Uh, basically that is the recipe, I eyeball it.
For about a pound or a pound and a half of ground beef, you mix in one egg, grate in 1/2 to 1 medium zucchini or yellow squash (I like to make it nearly half and half) and about 1/2 to 1 cup of Italian seasoned breadcrumbs (or regular breadcrumbs + about a tsp of Italian herb seasoning) - depending on how wet it is.
Spray the cupcake tins lightly, fill just to the edge, top with ketchup if you like, but they are good without it too, and bake 20 minutes at 400 degrees. Adult serving is 2.