These Spinach Stuffed Portobellos combine a flavorful mixture of three cheeses and spinach with hearty portobello mushrooms for an easy meat-free main dish.
Preheat the oven to 400ºF. Thaw the frozen spinach and squeeze out as much water as possible.
Place the squeezed spinach in a bowl and add the cottage cheese, mozzarella, feta, egg, garlic powder, salt, pepper, and crushed red pepper. Stir until everything is evenly combined.
Wipe any dirt or debris from the portobello mushrooms. Remove the stems. Brush a little oil over the mushroom caps and season with a pinch of salt. Place the mushrooms, gill sides up, on a baking sheet. Divide the spinach and cheese filling between the four mushrooms, mounding it inside the caps.
Bake the stuffed portobellos in the preheated oven for 25 minutes or until the cheese mixture on top is lightly browned. Mushrooms contain a lot of water, so don't be alarmed to see liquid seeping from the mushrooms.
Serve each spinach stuffed portobello drizzled with 2 Tbsp marinara sauce, if desired.