Saute the onion in the butter until it?s soft and golden brown. Remove it from the heat, and add it to the remaining filling ingredients, stirring till well combined.
Spoon the filling into the unbaked crust. Spread sour cream evenly over the top; this is best done by dolloping the sour cream atop the filling, then using a spatula, or the back of a spoon, to smooth down and connect the dollops. Sprinkle with paprika, i
Bake the quiche in a preheated 375°F oven for 55 to 60 minutes, or until it appears set almost all the way into the center, and has begun to brown slightly. It may crack, also; that?s OK. Remove it from the oven, and cool it on a rack for at least 20 minu