I’m going to make these again as soon as I can get some portobellos. Makes such a delicious side for grilled steaks. We just love these things! So glad I tried this veggie combo so I can feel like I’m eating “high on the hog” as my Dad used to say. Of course, you can use homemade mashed cauliflower, but the Birdseye was so good, and so convenient, why would you bother? 
This side dish is suitable for all stages of Atkins, Keto plans, Paleo and Primal as well.
INGREDIENTS:
3 Portobello mushrooms (mine were 3-oz. each)
3 T. olive oil
12 oz. pkg. frozen Mashed Cauliflower (I used Birdseye), Sour Cream & Chive
1 T. unsalted butter
¼ c. green onion, chopped
¼ c. Cheddar Cheese shreds
DIRECTIONS: Preheat oven to 350º. Line a pan with parchment (optional). Using a spoon, scoop the dark gills out of the mushrooms. With a basting brush, brush both sides of the mushrooms with olive oil. Set them curved side down on the pan. Pop them in oven for about 8-9 minutes.
While they are pre-cooking, cook the cauli-mash as instructed on the box. I microwaved mine. Remove film from tray and stir in the butter to mix and melt. Remove mushroom pan from the oven and spoon 1/3 of the mixture into each of the 3 mushrooms. Top each with 1/3 of the Cheddar cheese shreds. Finally, sprinkle the green onion evenly on all 3 servings. Return the mushroom pan to the oven and bake about 10 minutes more or just until cheese is melted.
NUTRITIONAL INFO: Makes 3 servings, each contains:
297 cals, 22.3g fat, 7.06g carbs, 2.33g fiber, 4.73g NET CARBS, 4.6g. protein, 261 mg sodium