Bring a large pot of salted water to a boil. Add pasta shells and cook until al dente. Drain and set aside to cool.
Heat 1 T butter and 1 T olive oil in a skillet over medium heat. Add the mushrooms and 1 tsp salt to the pan and saute until golden brown.
In a large mixing bowl, stir together the ricotta, spinach, artichoke hearts, mushrooms and cheese. Season with salt and pepper.
Spoon the filling into a large Ziploc bag with the tip cut off (large enough to let the vegetables pass through).
Set aside a 13 x9 baking dish. Squeeze the filling into the cooled pasta shells and add to the baking dish.
To make the sauce, melt the butter and 1 T olive oil to a medium-sized skillet. Add the shallots and saute until caramelized. Deglaze the pan with the wine, using a wooden spoon to scrape up browned bits off the bottom. When reduced by half, whisk in the cream and season with salt and pepper. Simmer until thickened.
Pour half the sauce over the prepared shells. Cover with foil and bake for 15-20 minutes, until filling is hot and bubbling. Serve with the remaining marsala sauce.