Bring a large saucepan of water to the boil and cook the penne as per the packet's instructions.
In a frying pan over medium heat, cook bacon until the fat starts to melt, add the garlic and onion then cook until the onion becomes soft and transparent. Add the mushrooms and butter and further cook until the mushrooms are soft.
Add the cream and season with salt and pepper to taste, simmer until the cream reduces by half. Stir through the cooked penne and serve with a sprinkling of parmesan cheese.