Gently heat the cream with the dried porcini over low heat for 15–20 minutes, until deeply fragrant. Do not let it boil.

Remove from the heat. If using, stir in the truffle oil, then finely chop the softened porcini and set aside.

Melt the butter in a wide skillet over medium heat. Add the shallots and cook until soft and translucent. Add the garlic and cook just until fragrant.

Stir in the chopped porcini and white pepper. Pour in the infused cream and simmer gently until slightly thickened and glossy.

Add the cheese and stir until melted and smooth. Season with salt to taste.

Cook the penne in well-salted water until just shy of al dente. Transfer directly to the sauce with a splash of pasta water and toss until perfectly coated and silky.

Finish with freshly grated cheese and fresh thyme leaves. Serve immediately.