Melt half the butter in a large cast iron skillet or frying pan over a medium high heat. Add the mushrooms and fry them for 10 minutes until softened and beginning to brown. Add the garlic and fry for another minute. Add plenty of salt.
While the mushrooms cook bring a pot of salted water to the boil and add the gnocchi. Cook according to packet instructions.
Once the mushrooms and garlic are cooked use a slotted spoon to transfer the gnocchi to the pan with the mushrooms. Reserve 100ml of the gnocchi cooking water. Toss the gnocchi with the mushrooms and add the rest of the butter, the thyme leaves and the parmesan. Toss again and add the gnocchi water as needed until the cheese and butter have melted and created a sauce. Serve with extra thyme leaves and parmesan.
Nutrition information is an estimate and will vary depending on the exact ingredients used.