Follow these simple steps to bake your batch of savory egg muffins:

1. Preheat and Prepare: Preheat your oven to 375°F (190°C). Generously grease a standard 12-cup muffin tin with oil or cooking spray, or line with silicone or parchment paper liners. This is crucial to prevent sticking.
2. Cook the Beef: Heat the olive oil in a large skillet or pan over medium-high heat. Add the ground beef and cook, breaking it apart with a spoon, until browned (about 5-7 minutes). Drain off any excess fat from the skillet.
3. Sauté Aromatics and Kale: Add the chopped onion to the skillet with the beef and cook for 3-4 minutes, until softened and translucent. Stir in the minced garlic and cook for another minute until fragrant.
4. Wilt the Kale: Add the finely chopped kale to the skillet. Cook, stirring frequently, for about 3-5 minutes, or until the kale has wilted down significantly and turned bright green. If the pan seems dry, you can add a tablespoon of water to help steam the kale.
5. Combine Beef and Kale Mixture: Once the kale is wilted, ensure the beef, onion, garlic, and kale are well combined in the skillet. Remove from heat and let it cool slightly.
6. Prepare the Egg Mixture: In a large bowl, crack the 12 eggs. Add the milk (or almond milk), salt, pepper, and any optional dried herbs. Whisk thoroughly until the yolks and whites are fully combined and the mixture is slightly frothy.
7. Assemble the Muffins: Evenly distribute the cooked beef and kale mixture among the 12 prepared muffin cups. Fill each cup about two-thirds full with the meat and vegetable mixture.
8. Add Egg Mixture: Carefully pour the whisked egg mixture over the beef and kale in each muffin cup, filling them almost to the top. If using optional cheese, sprinkle it over the top of each muffin now.
9. Bake: Place the muffin tin in the preheated oven and bake for 20-25 minutes, or until the egg muffins are set, puffed up, and lightly golden brown on top. A toothpick inserted into the center of a muffin should come out clean.
10. Cool and Serve: Once baked, remove the muffin tin from the oven and let the egg muffins cool in the tin for at least 5-10 minutes. This helps them firm up and makes them easier to remove. Run a thin knife or spatula around the edges of each muffin if needed, then carefully lift them out. Serve warm or allow to cool completely for storage.