clock clock iconcutlery cutlery iconflag flag iconfolder folder iconinstagram instagram iconpinterest pinterest iconfacebook facebook iconprint print iconsquares squares iconheart heart iconheart solid heart solid icon
Overhead photo of mashed potatoes in a silver bowl with mushroom gravy and parsley on top

White Cheddar Mashed Potatoes with Mushroom Guinness Gravy

  • Author: Jessie
  • Prep Time: 15 min
  • Cook Time: 30 min
  • Total Time: 45 minutes
  • Yield: Serves 4-6 1x
  • Category: Side Dish
  • Cuisine: American


This simple vegetarian mashed potatoes and mushroom gravy recipe gets a flavorful boost from a splash of Guinness.




  • 2 lbs. white potatoes, quartered (cut potatoes into even-sized pieces so they cook evenly!)
  • 4 Tablespoons unsalted butter
  • 1/2 cup milk
  • 1.5 cups shredded sharp white cheddar cheese
  • salt and pepper to taste


  • 2 Tablespoons unsalted butter
  • 10 oz. baby portobello mushrooms, sliced
  • Salt and pepper to taste
  • 1 teaspoon soy sauce
  • 2 Tablespoons flour
  • 2/3 cup stout (I used Guinness)
  • 2/3 cup vegetable stock
  • 2 Tablespoons chopped fresh parsley (optional, for garnish)



  1. Cook potatoes in salted, boiling water until easily pierced with a fork. (Prepare the gravy while the potatoes cook if you like). Drain cooked potatoes and set aside, then return empty pot to the stove over low heat.
  2. Add butter and milk to pot and warm until butter is melted.
  3. Return potatoes to pot and mash.
  4. Add shredded cheese, salt, and pepper to mashed potatoes. Stir until cheese has melted, then taste and add seasoning as necessary.

FOR THE GRAVY (Make this while the potatoes cook!):

  1. Melt butter in a large skillet over medium-high heat.
  2. Add mushrooms to skillet and cook, stirring occasionally, until mushrooms have reduced in size by about half.
  3. Add soy sauce, salt, and pepper and stir to combine.
  4. Add flour and stir to combine. Let cook 30 seconds or so until liquid has been absorbed.
  5. Add stout a little at a time, stirring constantly to break up any lumps of flour.
  6. Add stock and stir to combine. Bring to a low simmer and let cook, stirring occasionally, until gravy has thickened to desired consistency. You can let the gravy simmer on low heat until the potatoes are ready!


  1. Top the mashed potatoes with gravy and chopped parsley (optional) and serve immediately.


Good quality vegetable stock is a must here - use homemade if you have it, or look for an especially tasty low-sodium variety at the store!

Use beef stock or chicken/turkey stock in place of the vegetable stock if you like. You can omit the soy sauce if you use beef stock.

If the mushrooms look too dry before you add the flour, you can add an extra pat of butter to the pan.

A note about Guinness: All kegs worldwide are now vegan (the production process used to involve isinglass, a fish product used to filter beer) and reports indicate that the aim was for ALL Guinness (including bottles and cans) to be vegan-friendly by the end of 2017. I've seen a few unconfirmed reports that bottles and cans are indeed now vegan-friendly and reached out to the company to see if they can confirm this for us - I'll report back! If you're vegan/vegetarian and are worried about it in the meantime, get a growler filled with Guinness on tap somewhere (all vegan!) or look for a stout that isn't filtered with isinglass.

Keywords: side dish, thanksgiving, sides