Preheat oven to 350°F. Brown and crumble the sausage in a skillet over medium heat.
Using a 2 inch biscuit cutter or glass, cut 3 circles of sourdough bread from each slice of bread. Press each into the bottom of a muffin pan sprayed with vegetable spray.
In a bowl whisk the eggs with a pinch of kosher salt an cracked black pepper. Chop the fresh spinach, set aside.
Evenly distribute the crumbled sausage on the top of each bread circle. Top with chopped spinach. Pour the eggs evenly over each filled muffin mold. Top with healthy pinch of shredded parmesan cheese and bake for 18 minutes until cooked and tops are golden brown.