Cook pasta according to package instructions. While pasta is cooking chop the shallots, mushrooms and garlic, set aside. When pasta finishes cooking, transfer to a medium sized bowl and toss with a drizzle of olive oil, set aside.
Heat butter and olive oil in a large skillet on low heat until butter is melted. Then saute the shallots until the color becomes translucent and they smell fragrant. About 3 minutes.
Stir in the sliced mushrooms and cook 5-7 more minutes stirring occasionally until mushrooms are golden brown.
Take half of the spring of rosemary and chop it up, leave the rest on the spring. Add both, the chopped rosemary, and remaining spring to the mushrooms. Add chopped garlic and stir everything together. Let cook for an additional 2-3 minutes.
Turn the mushroom pan to medium heat and add the white wine to the mushrooms. It will be steamy! Let cook for 2-3 minutes, turn heat back down to low and then pour in the half and half and add the black pepper and pinch of nutmeg,