Remove stalks from all of the mushrooms and dice the stalks.

Dice the onion and combine with the diced stalks. Set aside.

Remove sausage links from their casing and cook ground sausage. Once fully cooked set aside to cool.

Add onion, stalks, and garlic to pan and cook down until onions are translucent. Transfer to a bowl and combine with sausage and cheddar cheese. Add salt and pepper.

Scoop sausage mixture into mushroom caps until you've filled all the mushrooms.

Place mushrooms on a baking sheet and bake at 350 degrees for 20 minutes.

Serve warm. Enjoy!