Preheat the oven to 375°F and grease a 12-Cup muffin pan with nonstick cooking spray.
Put eggs, cottage cheese, blue cheese, salt and pepper into a blender. Blend until smooth. Transfer to a large mixing bowl.
Heat 1 Tbsp olive oil in a medium pan over medium-high heat. Sauté prosciutto for 2-3 mins until slightly crispy. Remove from pan, let cool slightly and add to the mixing bowl.
Add 1 Tbsp olive oil to the pan, heat oil over medium-high heat until shimmering. Add mushrooms and cook until browned about 6 minutes.
Add onions and rosemary and cook until onions are translucent, about 3 minutes. Add baby spinach and cook until wilted, about 2 minutes.
Let mixture cool for about 5 minutes, then add to the egg mixture. Mix well.
Evenly divide egg mixture among muffin cups so they are about ¾ full.
Bake until a toothpick inserted comes out clean, about 20-25 minutes.
Let cool for 5-10 minutes before removing from the pan.