Start with making the pizza dough. Proof the yeast in the 1/8 cup warm water and 1/4 tsp sugar.
Put flour and 3/4 tsp salt in a bowl. Add water, yeast mixture and 1 tsp olive oil and knead dough to a ball with nice elastic and smooth consistency. cover with damp cloth and leave to rise for 1-1,5 hours until dough has doubled in size.
In the meantime, start preparing sauce and toppings. For the sauce, chop garlic and shallots very finely. Put approximately 3/4 of the mushrooms in a food processor and process to a puree.
Slice remaining mushrooms and fry them in 1 tbs of olive oil until browned, set aside.
Remove meat from sausage casing and fry in a frying pan until browned, working it with a wooden spoon to get nice small chunks of meat. Add fennel seeds the last 2 minutes. Set aside.
In a frying pan, heat 1/2 tbs butter and 1/2 tbs olive oil on medium-low heat and cook shallots and garlic without browning them, just until the raw aroma dissapears. Add mushroom puree and cook until most of the moisture has evaporized and the mixture starts to darken in color.
Add the wine, bring to a boil until alcohol has evaporized. Add chopped parsley, sage and vegetable stock and simmer until sauce has thickened. Season with salt and black pepper to taste.
Preheat oven to 500 degrees F.
Roll dough with rolling pin into a circle of about 12 inches and place onto pizza stone or baking tray. Bake the bare crust for 4 minutes. Remove from oven and coat with boscaiola sauce. Top with fried mushrooms, sausage and grated mozzarella. Bake another 6-8 minutes until edges are light brown and cheese has melted. Remove from oven, garnish with fresh parsley, a drizzle of olive oil and serve.