Preheat the oven to 350°F (175°C).
Grease a 12-cup muffin pan or line with silicone baking cups.
In a small saucepan, melt 1½ tablespoons of butter or ghee.
Whisk in the hot sauce, coconut aminos, and cayenne pepper until well combined. Remove from heat.
In a skillet over medium-high heat, melt the remaining ½ tablespoon butter or ghee.
Sauté the diced bell pepper and green onions for about 5 minutes until slightly softened.
Turn off the heat and add the spinach, cooked chicken, and prepared buffalo sauce. Stir until everything is evenly coated.
Divide the mixture evenly among the muffin cups.
In a medium bowl, whisk together the eggs, salt, and black pepper.
Pour the egg mixture over the chicken and vegetable filling.
Bake the Buffalo Chicken Egg Muffins for 18–20 minutes or until the eggs are fully set and a toothpick inserted into the center comes out clean.
Allow to cool slightly before removing from the pan.
Serve warm and enjoy.