Sauté onion in butter in a small skillet until tender, and set aside.
Cook bacon in a large skillet until crisp; drain bacon on paper towels. Crumble and set aside; discard drippings.
Combine onion, bacon, and cheese; sprinkle mixture evenly among 3 greased miniature muffin pans.
Combine eggs, pancake mix, half-and-half, salt, and pepper; stir well. Pour mixture evenly into prepared muffin pans, filling two-thirds full. Bake at 400° for 15 minutes or until tops of quiches are lightly browned. Remove from muffin pans; cool 5 minutes on wire racks.