One pot prawn, spinach and tomato pasta

Name: One pot prawn, spinach and tomato pasta
Prep time: 30 min
Cook time: 30 min
Total time: 1 h
Cuisine: European, Italian, Mediterranean
Ingredients: 1 tbsp extra virgin olive oil; 1 garlic clove, finely sliced; ½ tsp dried chilli flakes (optional); 400ml/14fl oz vegetable stock, made with ½ stock cube; 75g/2¾oz dried wholemeal pasta shapes, such as penne; 6 cherry tomatoes, halved; 50g/1¾oz baby spinach leaves; 125g/4½oz cooked and peeled prawns, thawed if frozen; ½ small lemon, finely grated zest only (optional); freshly ground black pepper