Make the Risotto: Heat the stock in a saucepan with the Italian mixed herbs. In a separate pan, fry the onion, mushrooms, and garlic in cooking spray until softened. Add the arborio rice and cook for a minute. Gradually add the hot stock, a ladleful at a time, stirring constantly and allowing the rice to absorb the liquid before adding more. Continue until the rice is cooked through but still has a slight bite, around 20-25 minutes. Season with salt and pepper. Remove from heat and stir in the parmesan cheese and beaten egg. Let the mixture cool completely.
Prepare the Breadcrumbs: Toast the bread slices and grind them into coarse crumbs using a food processor or blender. Season with salt and pepper.
Assemble the Arancini: Lightly oil your hands. Take approximately 2 tablespoons of the cooled risotto mixture and flatten it into a disc. Place a small amount of bolognese filling (with peas if using) in the center. Carefully fold the rice around the filling, forming a ball. Roll the ball in the breadcrumbs to coat evenly. Repeat with the remaining mixture, aiming for around 10 balls.
Bake the Arancini: Preheat the oven to 200°C (400°F). Arrange the breaded balls on a baking sheet lined with parchment paper and sprayed with cooking spray. Bake for 30 minutes, turning them over halfway through, until golden brown.
Make the Tomato Sauce (optional): While the arancini bake, heat some cooking spray in a pan and fry the onion and garlic until softened. Add the passata, stock, and balsamic vinegar (if using). Bring to a boil, then reduce heat and simmer until the sauce thickens slightly.
Serve: Enjoy the baked risotto balls warm with the tomato sauce for dipping.
Tips:
For a vegetarian option, use vegetable stock and a vegetarian bolognese filling or roasted vegetables.
You can adjust the amount of filling to your preference.
Leftover arancini can be stored in the fridge for up to 3 days and reheated in the oven or microwave.
Feel free to experiment with different fillings, such as pesto, spinach and ricotta, or roasted vegetables.
