Cut a prosciutto slice in half and line one muffin well using both pieces. Repeat until all of the muffin wells are lined.
In a large bowl, combine the eggs, serrano pepper, red onion, baby portobello mushrooms, and spices and mix well. Pour the egg mixture into the prosciutto-lined wells and top with crumbed chèvre if using.
Bake at 375°F for 15 minutes.
Notes
If not using prosciutto, be sure to add more salt.