- Place bacon in a large pan and cook over medium-high heat until evenly brown. Remove the bacon from the pan, dice and set aside.
- Preheat the oven to 200°C.
- Remove the mushroom stems, set the caps aside and chop the stems finely.
- In the same large pan, melt the butter over medium heat. Add the chopped stems, garlic and onion and cook until the onion is soft. Remove from heat.
- In a bowl, stir together the mushroom stem mixture, bacon and 1/2 cup of the cheddar and season with salt and pepper to taste. Mix well and scoop the mixture into the mushroom caps.
- Place the mushrooms on a lined baking sheet and bake for 10 – 15 minutes, or until the cheese has melted.
- Remove the mushrooms from the oven, and sprinkle with the remaining cheese and chopped chives.