"Paleo. Breakfast. On-the-go. For some reason individual cupcake liners don't work so well for these little quiches. Grease the tin with olive oil or butter."
1Preheat oven to 450 degrees F (230 degrees C). Grease 12 muffin cups with olive oil.
2Place bacon in a large skillet and cook over medium-high heat, turning occasionally, until evenly browned, 5 to 10 minutes. Transfer bacon to a paper towel-lined plate to drain.
3Saute onion, spinach, and mushrooms in the same skillet until onions are soft, 5 to 10 minutes. Remove from heat and cool slightly.
4Blend onion mixture in a blender until smooth. Beat onion mixture, eggs, feta cheese, and bacon together in a bowl until batter is well-combined. Pour batter into prepared muffin cups.
5Bake in the preheated oven until a toothpick inserted into the center of a muffin comes out clean, about 35 minutes.