- With the rack in the middle position, preheat the oven to 180 °C (350 °F).
- Remove the stem from the mushrooms and chop finely. Set aside.
- Lightly oil the mushroom caps and place them, opening side up, in a baking dish. Season with salt and pepper.
- In a non-stick skillet, brown the chopped mushrooms with the bacon and shallots in the oil. Add the garlic and cook for 1 minute. Deglaze with the broth and pour into a bowl. Add the mascarpone cheese and breadcrumbs and stir to combine. Season with salt and pepper.
- Generously stuffed the mushrooms with the cheese mixture and top with a piece of Riopelle cheese, pressing slightly. Bake for 30 to 35 minutes or until the cheese is golden brown.