Cook the chopped bacon in an oven-safe pan over medium heat for about 10 minutes, or until golden and crisp.
Add the diced onion and stir to combine. Cook for about 5 minutes, stirring occasionally, until softened. Stir in the spinach and cook for 1–2 minutes, just until wilted.
In a medium bowl, whisk together the eggs, half & half, salt, and black pepper.
Preheat the broiler. Pour the egg mixture into the pan with the bacon, onion, and spinach. Stir gently to combine. Cook for 5 minutes, or until the eggs are mostly set.
Arrange the pepper jack cheese slices evenly over the top. Transfer the pan to the oven and broil for 2–3 minutes, until the cheese is melted and golden.
Remove from the oven, let cool slightly, then slice into quarters and serve.
Notes
Storage: Store leftovers in an airtight container in the fridge for up to 4 days.
Reheating: Warm slices in the microwave or in a 350°F oven until heated through.
Substitution Ideas: Swap pepper jack with cheddar, mozzarella, or your favorite cheese. Use cooked sausage or ham instead of bacon if you like.