Preheat oven to 180˚C. Slice the top third of the head of garlic off. Place on a square of tinfoil. Drizzle with a little olive oil and season with salt. Wrap up the garlic tightly and place in the oven for 1 hour. After an hour remove the garlic from the oven and squeeze the roasted cloves out of their skin. Heat a drizzle of olive oil in a frying pan and fry the mushrooms with 2 tsp curry powder. Season and set aside in a bowl. In the same pan add the remaining 2 tsp of curry powder, toast spices for a minute and then add the tin of crushed tomatoes. Cook the tomatoes down until they reduce to a thick sauce. Season. Toast the naan breads in a hot dry pan until both sides are crisp. Place naan breads on a baking tray and begin assembling the pizzas. Spread a small amount of the curried tomato sauce on each naan. Top with roughly torn pieces of mozzarella, spiced mushrooms, fresh chilli and the roasted garlic. Roast them in the oven until the cheese is bubbling and golden brown. Top pizzas with diced tomato & onion salsa and fresh coriander. Slice and serve.