Place potatoes into a large saucepan and cover with water, bring to the boil and cook for 15 minutes or until tender.
Meanwhile for the Caramelised Onions, melt butter in a large frying pan, add frozen Birds Eye Chopped Onions and cook for 10 minutes stirring occasionally. Add brown sugar and continue to cook for a further 5 minutes or until caramelised. Stir in balsamic vinegar and season to taste with salt and pepper.
Drain potatoes and return to hot saucepan, mash with a potato masher. Stir in cream and egg yolks and beat with a fork until fluffy. Season to taste with salt and pepper.
Spoon ¼ cup of potato into small greased ovenproof pots and spoon 1 teaspoon caramelised onion on top. Lightly spray with oil. Place on a baking tray and bake in a preheated oven at 200ºC for 15 minutes. Serve potato pots garnished with a small sprig of thyme.