In a frying pan over medium heat, saute the mushrooms in 3 tablespoons of butter until limp. Stir in the crushed crackers, then turn into a well-greased 9-inch pie pan. Press mushroom mixture evenly over pan bottom and up the sides. Melt remaining 2 tablespoons utter, add onions, and saute until limp. Spread onions over crust; sprinkle evenly with the shredded cheese. In a blender, whirl the cottage cheese, eggs, and cayenne until smooth. Pour into crust and sprinkle with paprika. Bake in a 350 degree oven until a knife inserted in the center comes out clean, about 20 to 25 minutes. Let stand 10 to 15 minutes before cutting. Serve this savory quiche with a fresh spinach or mixed green salad.