Preheat your oven to 180°C. Prepare a muffin tin by greasing it with a small amount of oil or lining it with paper liners.
In a bowl, crack the eggs and beat them thoroughly until well mixed. Combine the grated cheddar cheese with the beaten eggs and mix until smooth.
Add the finely diced red and green bell peppers, finely diced onion, and chopped baby spinach into the mixture. Season with salt, black pepper, dried oregano, and dried thyme. Stir until all the ingredients are evenly distributed.
Using a ladle or a measuring cup, pour the egg mixture into the muffin cups, filling each cup to about two-thirds of its capacity.
Place the muffin tin into the preheated oven and bake for approximately 20 minutes, or until the egg muffins are fully set and have a slight golden hue on the top.
Once they’re done baking, take the muffin tin out of the oven and allow the egg muffins to cool within the tin for a few minutes. Gently remove the egg muffins from the tin and transfer them to a wire rack to cool completely.
Serve your egg muffins while still warm or at room temperature. For storage, keep them in an airtight container in the refrigerator for several days.