Step 1Preheat oven to 200°C. Line a baking tray with baking paper. Place potato slices, in a single layer, on prepared tray. Drizzle with 2 teaspoons of oil. Season with cracked black pepper. Place garlic cloves on tray. Bake for 35–40 minutes. Remove garlic after 20 minutes.
Step 2Heat 2 teaspoons of oil in a medium non-stick frying pan over high heat. Then cook the French-trimmed lamb racks, turning, until browned. Place lamb on a separate tray and bake for the last 15 minutes of potato cooking time. Cover and rest for 5 minutes.
Step 3Meanwhile, squeeze garlic flesh from skins, discard skins. Finely chop up the garlic. Warm leftover oil in small non-stick frying pan over a medium-high heat. Sauté onion for 5 minutes, or until softened. Add wine and boil until reduced by half. Add garlic, cream, stock cube and 1 cup of water, and bring to the boil. Reduce heat and simmer for 10 minutes, or until sauce thickens and is reduced by half.
Step 4Combine the cornflour and 1 tablespoon water in a small bowl. Add to sauce and stir until mixture boils and thickens.
Step 5Meanwhile, blanch beans, broccolini and zucchini in a medium saucepan of boiling water for 2–3 minutes. Drain. Serve lamb with potatoes, greens and onion cream sauce. Scatter with basil leaves.