Preheat your oven to 350°F (175°C).

Grease a 12-cup muffin tin with beef tallow or butter to prevent sticking.

If you haven't already, cook the bacon or sausage in a skillet over medium heat until crisp or fully cooked. Drain and dice into small pieces.

Prepare Egg Mixture: In a large bowl, whisk together the eggs until well beaten. If using, stir in the diced bacon or sausage. Season with a little salt if needed.

Fill Muffin Cups: Evenly distribute the egg mixture among the greased muffin cups, filling each about two-thirds full to allow room for the egg to expand as it cooks.

Bake: Bake in the preheated oven for 20-25 minutes, or until the egg muffins are set and lightly golden on top. A toothpick inserted into the center should come out clean when they are done.

Cool and Serve: Let the egg muffins cool in the pan for a few minutes before removing them. Use a knife or spatula to gently lift them out of the tin.

Serve warm, or cool completely and store in the refrigerator for a quick snack or breakfast throughout the week.