Heat the oil in a large frying pan and sauté the onion until soft.
Add the turkey and fry until golden.
Mix in the carrots, peas, thyme and mushroom soup.
Bring to the boil, then reduce heat and simmer for 15 minutes.
Mix the flour, polenta, salt and baking powder.
Add the butter and rub in with your fingertips until mixture resembles coarse breadcrumbs.
Whisk the eggs and milk, and stir into the flour mixture until well combined.
Spoon turkey mixture into a pie dish and spread on the topping.
Bake in a preheated 200 °C oven for 20 to 25 minutes or until golden. Serve with rice.
If you cannot find turkey breast fillets, use chicken breast fillets instead.