Preheat oven to 375°F. Lightly grease a 24-cup mini muffin pan with a little oil.
Heat 1 teaspoon oil in a skillet over medium heat. Sauté bell pepper until softened, about 3 minutes.
Stir in spinach and cook until wilted. Transfer vegetables to a plate to cool slightly.
Whisk eggs, milk, salt, pepper, garlic powder, and paprika in a large bowl until smooth.
Fold in cheese, bacon, green onions, and the cooled vegetables.
Divide mixture among muffin cups, filling each nearly to the rim.
Bake 14–18 minutes, until puffed and the centers are just set.
Rest 5 minutes. Loosen edges and lift out. Serve warm or cool for meal prep.