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High-Protein Beef & Spinach Stuffed Portobellos with Savory Mushroom Gravy

October 7, 2026 by
Rima fit food

A rich, savory, smart-carb dinner that delivers pure comfort food flavors! Large portobello caps are filled with a high-protein mixture of ground beef, fresh spinach, and creamy ricotta, topped with melted mozzarella, and smothered in a rich pan-made mushroom and onion gravy. Using butter and a touch of tangy mustard in the roux gives the gravy incredible depth without needing heavy cream!

Prep time: 15 mins

Cook time: 25 mins

Yield: 2 large stuffed portobellos

Ingredients

Stuffed Portobello Caps

  • 2 large portobello mushroom caps, stems removed (save stems for gravy!)

  • 1/2 lb extra-lean ground beef, cooked

  • 1 cup fresh spinach, finely chopped

  • 1/4 cup ricotta cheese or cream cheese

  • 1/2 tsp garlic powder

  • 1/2 tsp onion powder

  • Salt and black pepper, to taste

  • 1/2 cup shredded part-skim mozzarella cheese

Savory Mushroom Pan Gravy (No Cream)

  • 1 tbsp butter

  • 1/2 small red or yellow onion (or shallot), finely diced

  • Reserved portobello mushroom stems, finely chopped

  • 1 tbsp flour (all-purpose, or cornstarch)

  • 1 cup beef broth or vegetable broth

  • 1 tsp Dijon or yellow mustard 

  • Salt and black pepper, to taste

Step-by-Step Instructions

  1. Prepare the Stuffed Mushrooms: Clean the portobello caps and gently remove the stems (finely chop the stems and set aside for the gravy).

  2. Make the Filling: In a bowl, combine the cooked ground beef, chopped fresh spinach, ricotta cheese, garlic powder, onion powder, salt, and pepper. Mix thoroughly until cohesive and creamy.

  3. Stuff & Bake: Divide the beef-spinach filling evenly between the two portobello caps, pressing down gently. Top with shredded mozzarella cheese. Bake on a parchment-lined tray at 400°F (200°C) for 15–18 minutes until the mushrooms are tender and the mozzarella is melted and bubbly.

  4. Make the Savory Gravy: While the mushrooms bake, melt 1 tbsp of butter in a skillet over medium heat. Add the diced onion and chopped mushroom stems, sautéing until soft and fragrant. Sprinkle 1 tbsp of flour over the onions and mushrooms, stirring for 1 minute to create a roux. Slowly whisk in the broth, followed by 1 tsp of mustard. Simmer on medium-low until thickened to a glossy gravy consistency, then season with salt and pepper.

  5. Serve: Place a hot baked portobello cap on a plate and pour a generous ladle of warm mushroom gravy over the top!