In a frypan, melt 50g butter and 1 tablespoon olive oil and add the fresh mushrooms. Season with salt and pepper and saute until done. Drain the porcini and add to the mushrooms. Reserve.
Melt the remaining butter in a large frypan and saute the shallot until soft. Add rice and stir to coat with butter. Add the white wine and let evaporate.
Add the pumpkin and stir. Start adding the hot stock a little at a time, stirring until absorbed. When rice is done, remove from heat and stir in the cheese.
Serve the risotto, topped with a few tablespoons of the mushrooms.