Place the mushrooms, stalk side up, in a large roasting tin. Scatter with the garlic, drizzle with the oil and season generously with salt and pepper. Place in a preheated oven, 180°C (350°F), Gas Mark 4, for 18–20 minutes or until tender and juicy.
Meanwhile, cook the pasta in a large saucepan of boiling water for 10–12 minutes, or according to the packet instructions, until al dente.
Put the breadcrumbs, lemon rind, half of the parsley and the chilli flakes, if using, into a large, nonstick frying pan over a medium high heat. Dry-fry for 4–5 minutes, or until golden brown and crispy, stirring continuously. Set aside.
Remove the mushrooms from the oven and cool slightly, then roughly chop. Drain the pasta and toss with the mushrooms, lemon juice and remaining parsley. Season with salt and pepper to taste, then heap into serving bowls. Scatter over the breadcrumbs and serve immediately with Parmesan, if liked.