Cut bacon into small strips and cook on medium heat for 2-3 minutes
Cut onion, add to the bacon and cook until goldish and crispy
Cut spinach and add to the onion-bacon mix, cook 5-6 seconds. Spinach becomes soft very quickly
Remove from the heat
Mix together eggs, yogurt, and mozzarella cheese
Add bacon mixture to eggs mixture, salt, and pepper for taste
Distribute between 4 individual baking cups
Bake in a preheated to 350*F (175*C) for 25-30 minutes