Preheat oven to 375º F.
Wash potatoes, prick several times all over with a fork, place on baking sheet and bake for 1-1/2 hours.
When cooked, remove from oven and cut in half lengthwise and let cool slightly.
When potatoes are still warm, using a box grater, grate them into a bowl (but not the skin).
Add the egg, salt and Italian herbs.
Mix to just combine.
Sprinkle 1/2 the flour onto your counter (save a bit of flour for rolling later).
Place the potato mixture onto the flour.
Flatten slightly with your hand, add flour on top (small amounts at a time) and incorporate into mixture.
Keep adding flour to the potatoes to form a dough (pressing down and folding several times).
Once dough is formed, shape it into a ball.
Divide ball into 3.
Roll each section into a 3/4 inch rope (use some of the leftover flour to prevent sticking).
Using a pastry scraper (or knife) cut each rope into 1 inch pieces, and set on a floured baking sheet until ready to cook.
Clean and slice mushrooms.
In a frying pan heat 1 tbsp. olive oil over medium heat.
Add the mushrooms and cook for 2 minutes.
Add garlic, 2 stalks of rosemary, and cook for 5 minutes.
Season with salt and pepper and set aside till ready to use.
Bring a pot of water to a boil.
Add gnocchi pieces gently to the boiling water and cook for approximately 2 minutes, stirring gently (they should float to the top).
Using a slotted spoon, remove gnocchi from water and place in an oiled bowl.
In a non-stick frying pan, heat 1 tbsp. of olive oil over medium heat.
Add gnocchi, and brown on all sides.
Add 1 tbsp. of rosemary leaves and butter.
Add the cooked mushrooms.
Cook for approximately 1 more minute (to heat the mushrooms).
Place into serving bowl.
Add some freshly grated black pepper.
Garnish with freshly grated cheese.