Bake eggs directly in a pepper for a gorgeous breakfast dish that all will enjoy. Use any colored bell pepper, just be sure to remove the seeds.
Preheat oven to 375°F.
Halve peppers lengthwise; remove and discard seeds. Place the peppers cut-side up in an 8-inch-square microwave-safe dish. Microwave on High until just tender, 2 1/2 to 3 minutes. Pat dry and sprinkle with salt.
Whisk eggs, milk and pepper in a medium bowl.
Heat oil in a medium skillet over medium-high heat. Add onion and cook, stirring, until softened and beginning to brown, about 2 minutes. Add spinach and cook, stirring, until wilted, 1 to 2 minutes more. Divide the spinach mixture among the pepper halves. Sprinkle with feta, then top with the egg mixture. Bake until the filling is set, 30 to 35 minutes.