Spray a muffin tin with cooking spray and set aside.
Heat oil in a large skillet, then sauté sausage and red bell pepper for 2-3 minutes.
Add spinach, onion, and garlic, and sauté for 2-3 minutes, just until the meat is cooked and the vegetables are softened. Turn off the heat and set aside.
In a large bowl, beat the eggs, milk, cheese, thyme, salt, and pepper.
Divide the meat and vegetable mixture evenly among the prepared muffin tin cups, setting aside 1/4 cup of the mixture.
Pour the egg mixture over each muffin tin cup, dividing evenly and leaving a little bit of room at the top, as the eggs will puff up.
Top each with the reserved meat and vegetable mixture
Bake for 15-20 minutes, until the centers are just set (or a toothpick inserted into the center comes out clean).
Allow to cool in the muffin tin for 5 minutes before serving.
Notes
Makes 12 egg bitesStorage: allow to cool, then store in an airtight container in the refrigerator for up to 4 days or in the freezer for up to 2 months.