Rinse the spinach thoroughly. Allow to dry before chopping into fine bits. Slice the bacon into small squares too. Reserve for later use.
Set a frying pan over a medium-high heat. Pan fry the bacon bits in hot olive oil for 2 minutes. Toss the chopped onion in and stir well. Once the onion turns transparent and tender, mix in the spinach. Whisk the mixture together for 2 more minutes before turning off the heat.
Crack the eggs in a bowl and beat thoroughly. Whisk along with the sour cream. Adjust the taste with a decent amount of salt and pepper. Gently throw in the chopped or diced cheddar cheese. Stir with a spoon until combined.
Incorporate the spinach mixture with the egg mixture. Place in a baking dish. Stir the mixtures thoroughly. Top with some extra cheese if desired.
Bake the quiche batter in the oven for half an hour. Let the quiche dry and solidify. When the quiche is cooked and the cheese turns brown and melted, remove from the oven. Make 8 slices and enjoy warm!