Cook the pasta in a large saucepan of boiling salted water until al dente, drain, then toss through some olive oil. Set aside.
For the sauce, heat the oil and butter in a heavy-based frying pan over low heat and cook the shallots until soft and translucent. Add the garlic, thyme and button mushrooms and cook until the mushrooms have softened and the liquid has reduced. Add the wine and simmer until the liquid has evaporated.
Add the porcini mushrooms and stock and simmer until the liquid has reduced by half. Stir through the cream and spinach and simmer for 2–3 minutes. Remove the sauce from the heat and check the seasoning.
Serve the sauce on top of the pasta with a good sprinkle of the pecorino, a grind of black pepper and garnished with the rocket leaves.