Heat the oven to 400°F. Arrange the pepper halves cut-side up in a baking dish and brush with half the olive oil.
Bake the peppers for 10 minutes, until they begin to soften but still hold their shape.
Warm the remaining oil in a skillet over medium heat. Cook the onion for 3 minutes, add the spinach, and stir until wilted.
Whisk the eggs with salt and pepper, then pour them into the skillet. Stir gently for 1 to 2 minutes, until softly set.
Divide the egg mixture among the peppers and top with cheddar. Bake for 10 to 12 minutes, until the cheese melts and the eggs are set in the center.
Notes
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