Instructions

1. Cook the pasta according the packet instruction.
2. Meanwhile, put the garlic, watercress, lemon zest, walnuts and cheese into a food processor and whiz to a smooth paste. Slowly drizzle in the olive oil and some water to make a thick paste. Season with salt and pepper. Taste, add adjust it to your liking.
3. When the pasta is cooked, drain it, then put it back into the pan. Add most the pesto, mix well. Fold in a handful of watercress leaves, then serve with freshly ground pepper and some chopped walnut pieces.
4. Keep the rest of the pesto for other dishes.