Tortellini with Mushrooms, Spinach and Italian Sausage

pkg. fresh 3 cheese tortellini

big spoonful (or two) of pesto

(2-3) mild or spicy Italian sausages

sliced mushrooms

few garlic cloves, chopped or crushed (optional)

chicken stock or water

cream (half & half or heavy)

few handfuls torn baby spinach

grated Parmesan cheese, for serving