New Potato, Fennel, Onion And Mushroom Pie With Mozzarella

• 5 mm
• 4 onions (finely chopped)
• 2 bulbs fennel roughly (chopped)
• 2 garlic (cloves crushed)
• 1 black pepper (freshly ground)
• 575 gr potatoes scrubbed (new)
• 80 gr flat mushrooms (sliced)
• 65 gr packs mozarella cheese (sliced)
• 60 gr vegetarian cheddar cheese (freshly grated)
• 30 ml olive oil