Preheat oven to 180°C. Use a regular 12-cup muffin pan. Grease pan lightly with oil.
In a large bowl, beat eggs until smooth. Add milk, salt and cheddar cheese and mix. Stir in sweet peppers, garlic, onion and thyme into the egg mixture. Ladle the egg mixture into each lightly greased muffin tin until ¾ full.
Bake for 30 minutes. Remove from the oven, let the muffins cool for 30 minutes before removing them from the pan. Makes roughly 12 muffins. 2 muffins is a serving.