• Preheat oven to 350°F/ 175 degrees C. Spray foil lined baking sheets with non-stick cooking spray or line baking sheet with parchment paper.
• Wash mushrooms, remove stems and set the stems aside . ( *The stems easily pop off when you gently pull them to the side). Finely chop HALF the stems.
• With a small spoon, gently scoop out mushroom caps so there is room for stuffing. Add mushroom cap scrapings to finely chopped stems in a small bowl.
• In a microwave safe bowl, cook butter, onion, garlic and only HALF mushroom stems and scrapings from the mushroom for 4 minutes. You can save the other half for soup stock, eat them or discard in the compost bin.
• In a medium bowl, mix together instant mashed potatoes, cheese, bacon bits, sauerkraut, sour cream, salt, pepper. * Eliminate bacon bits if making vegetarian.
• Then add the onion, mushroom stem, butter garlic mixture and stir until combined.
• Place mushroom caps on prepared baking sheet and stuff mushrooms then stuff caps using a small spoon.

  Sprinkle with parmesan cheese, dividing evenly between all the mushrooms.
• Bake until for 15 - 20 minutes or until mushrooms are golden and cooked through.

Garnish

• Garnish with parsley or fresh dill, and sour cream  if desired.