Preheat your oven to 180°C (350°F). Lightly grease the muffin tin with butter or spray to prevent sticking.
In a large mixing bowl, crack all the eggs and whisk vigorously until the yolks and whites are fully combined, creating a smooth, uniform mixture.
Add the milk or cream to the eggs and whisk again to incorporate, making the mixture light and slightly frothy.
Stir in the shredded cheese, chopped bell peppers, spinach, chopped herbs, salt, and pepper. Mix well to evenly distribute all the add-ins throughout the batter.
Pour or spoon the egg mixture evenly into each muffin cup, filling them about three-quarters full to allow room for puffing up during baking.
Place the muffin tin in the oven and bake for 20-25 minutes, or until the tops are golden brown and the muffins feel firm when gently pressed.
Remove the muffins from the oven and let them cool in the tin for about 5 minutes. They will firm up slightly as they cool, making them easier to remove.
Run a knife or spatula gently around the edges of each muffin to loosen, then carefully lift them out of the tin.
Serve the egg muffins warm or at room temperature, enjoying their fluffy texture and savory flavor.
