Preheat Oven: Preheat your oven to 400°F (200°C). Grease a 12-cup muffin tin with cooking spray or butter.
- Prepare Hash Brown Base: In a bowl, combine the thawed hash browns with 1/4 cup of the shredded cheddar cheese. Press the mixture evenly into the bottom and up the sides of each muffin cup to form a nest.
- Bake Hash Brown Cups: Bake in the preheated oven for 20 minutes or until the hash browns are golden brown and crispy.
- Prepare Egg Mixture: While the hash browns are baking, whisk together the eggs, milk, salt, and pepper in a bowl. Stir in the remaining shredded cheddar cheese, cooked bacon, and diced vegetables if using.
- Fill Hash Brown Cups: Once the hash brown cups are baked, remove them from the oven. Reduce the oven temperature to 350°F (175°C). Carefully pour the egg mixture into each hash brown cup, filling them evenly.
- Bake Egg Cups: Return the muffin tin to the oven and bake for an additional 15–18 minutes, or until the eggs are set and lightly browned on top.
- Cool and Serve: Allow the egg cups to cool for a few minutes before removing them from the muffin tin. Garnish with fresh herbs if desired and serve warm.