For a more intense basil flavor, gently bruise the basil leaves before blending. Toast the walnuts lightly before adding them to the pesto for a nuttier taste. Feel free to experiment with different types of mushrooms or add other vegetables like sliced bell peppers or onions to the sauté. If you don't have naan bread, pita bread or flatbread can be used as a substitute. A touch of red pepper flakes can add a subtle heat to the pizza.