Prepare Sweet Potatoes:

• Preheat the oven to 400°F (200°C).
• Line a large baking sheet with parchment paper.
• Toss sliced sweet potatoes with olive oil, salt, and pepper in a large bowl.
• Arrange the sweet potato slices in a single layer on the prepared baking sheet.
• Bake for 15-20 minutes, or until slightly softened.

Prepare Spinach Filling:

• Heat olive oil in a large skillet over medium heat.
• Add the chopped onion and cook until softened (about 5 minutes).
• Add the minced garlic and cook for another minute.
• Add the spinach and cook until wilted (about 2-3 minutes, or if using frozen, just heat through).
• Remove from heat and set aside.

Prepare Egg Mixture:

• In a medium bowl, whisk together the eggs, milk, salt, pepper, and nutmeg (if using).

Assemble the Bake:

• Lightly grease an 8×8 inch baking dish.
• Arrange half of the baked sweet potato slices at the bottom of the baking dish.
• Spread the spinach mixture evenly over the sweet potato layer.
• Sprinkle crumbled feta cheese (if using) over the spinach.
• Pour the egg mixture evenly over the spinach and cheese.
• Arrange the remaining sweet potato slices on top of the egg mixture.

Bake:

• Bake for 30-35 minutes, or until the egg mixture is set and the top is lightly golden.

Cool and Serve:

• Let the bake cool slightly before slicing and serving.