Step 1

Preheat the oven to 400ºF. Thaw the frozen spinach and squeeze out as much water as possible.

Step 2

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.

Step 3

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.

Step 4

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.

Step 5

Serve each spinach stuffed portobello drizzled with 2 Tbsp marinara sauce, if desired.