Step 1 Heat oil in a non-stick casserole dish or large pan and cook onion until softened. Add chicken and cook over a high heat until it has lost its pink colour.

Step 2 Add carrots, mushrooms, mixed herbs, stock, tomatoes, sugar, flour and paste and bring to the boil. Reduce heat then cover and simmer for 35 minutes.

Step 3 Mix a little of the cooked sauce with cornflour to form a paste. Add to the casserole and stir until thickened. Add olives.

Step 4 To make polenta base, bring water to the boil. Reduce heat to low and add polenta. Stir for 4-5 minutes until thickened. Stir in parmesan cheese.

Step 5 Spread onto a lightly-greased pan and form into a 24cm round. Cook in a preheated oven at 190°C for 10 minutes.

Step 6 Add pizza topping and cook for a further 10 minutes. Serve garnished with fresh basil or flat-leaf parsley.