Soak the porcini in just enough boiling water to cover for 10 minutes. Drain, reserving the liquid, and roughly chop the porcini.
Dust the veal escalopes with the flour. Heat the butter and the olive oil in a frying pan and cook the escalopes for 2–3 minutes on each side, until just cooked through. Remove from the pan and keep warm.
Add the garlic, onion and mushrooms to the pan and sauté for 4–5 minutes, until the onion is soft.
Pour in the wine and bubble for 2–3 minutes, then pour in the cream and 2–3 tablespoons of the reserved porcini liquid.
Bring to the boil, then stir in the porcini and spinach and some salt and pepper. Return the escalopes to the pan and cook for 1 minute before serving with mashed potatoes.