Grilled chicken salad with zingy buttermilk dressing

Ingredients

• 2 thick slices wholegrain sourdough, cubed
• 125 gram can chickpeas, rinsed, drained
• 2 chicken breast fillets, butterflied
• 1 tablespoon olive oil
• 1 leek, trimmed, sliced thickly
• 120 gram punnet baby corn, halved lengthways
• 1 radicchio, trimmed, cut into wedges
• 1 baby cos lettuce, trimmed, cut into wedges
• 2 thin slices prosciutto, grilled, broken
• 1 1/2 tablespoon shaved parmesan
• basil leaves to serve
• Dressing
• 1/3 cup buttermilk
• 1 tablespoon lemon juice
• 1 tablespoon chives, chopped
• 1 small garlic clove, crushed
• 1 teaspoon finely grated lemon zest, plus extra to serve