Fall Harvest Breakfast Skillet

Ingredients

• 1 tablespoon olive oil
• 1 1/2 tablespoons butter, divided
• 1 (8-ounce) package mushrooms, sliced
• 2 cloves garlic, chopped
• 1/2 teaspoon dried thyme
• 1/2 teaspoon red chili flakes, plus more, to taste, for topping
• kosher salt, to taste
• black pepper, to taste
• 4 cups fresh spinach
• 4 eggs
• sea salt, optional, to taste, for serving