Wash and pat dry the mushrooms. Gently slice out the stem. Brush the melted butter all over both mushrooms and place onto a foil lined baking sheet.
In a large pan, heat the olive oil over medium heat. Add the garlic and baby spinach. Cook until the spinach is wilted, then add the sour cream and Parmesan cheese. Stir in the brown rice. Season with salt and pepper.
Gently add the mixture to each of the mushrooms.
Bake for 10 minutes, then sprinkle with the Monterrey jack cheese. Bake for another ten minutes, until the cheese is melted and the mushrooms have shrunk.
Serve immediately.
Recipe Notes
Utilize your toaster oven if you have one! I made mine in our toaster oven, set at 375 and it cooked wonderfully.