1Finely chop mushrooms by hand, or alternatively, pulse in a food processor until finely chopped.
2Heat 1 tbs oil in a large non-stick frying pan over high heat. Add mushrooms and cook, stirring often, for 8 minutes or until all moisture has evaporated.
3Bring stock to the boil in a medium saucepan. Heat remaining oil in a large saucepan over medium heat. Add onion and garlic, cook, for 5 minutes until soft. Stir in rice and cook, for 2 minutes or until grains look glassy. Stir in boiling stock. Reduce heat to low, cover and simmer, stirring every 5 minutes, for 20 minutes or until rice is tender and risotto thickened. Stir in mushrooms. Place into a heatproof bowl refrigerate until cold.
4Stir parmesan, mozzarella and basil into risotto, season. Roll 1 tbs chilled rice mixture into a ball. Repeat with remaining mixture. Coat balls, one at a time in flour, egg and then breadcrumbs. Cover and refrigerate for 1 hour until firm.
5Add enough oil in a large saucepan to reach a depth of 5cm. Heat oil over medium-high heat, deep- fry arancini balls 6-8 at a time in hot oil until golden. Using a slotted spoon transfer to a plate lined with paper towel. Keep warm in a warm oven. Repeat in batches with remaining mixture, reheat oil between batches. Serve with lemon wedges.