Preheat oven to 375°F. Coat two 24-hole nonstick mini muffin pans with cooking spray (or use just one pan and cook in two batches).
Combine all ingredients in a large bowl; spoon about 1 heaping tablespoon egg mixture into each prepared hole, making sure to stir mixture after filling each one.
Bake until bottoms are golden brown and quiche are cooked through, about 15 minutes. Remove pan(s) from oven and let quiche cool for a few minutes in pan(s); remove quiche to a wire rack to cool more (and repeat with remaining ingredients if necessary). Yields 1 quiche per serving.