Start by cutting 4 medium potatoes into a rough 1-2 cm cubes.

Put them in a microwave bowl and cover with boiling water. Cook on full power for 10 minutes then drain

Peel the onions, cut in half and slice.

Fry the onions over a medium heat with 1 tablespoon of the oil for a few minutes until golden. Then add the crushed garlic for a minute.

Transfer the onion onion mixture to a bowl and add the remaining oil and butter to the frying pan.

Add the cubed potatoes and fry over a medium heat for 5 to 10 minutes until nicely coloured. Then add the onion to the potatoes to warm through.

Put the diced potatoes in a saucepan and pour over boiled water to cover. Cook the potatoes on the hob or in the microwave for 5 minutes then drain.

Add the potatoes to the oven dish and turn to coat in the oil. Roast for 20 minutes.

Turn the potatoes and add 2 sliced onions, 2 cloves of sliced garlic and the chopped rosemary.

Roast for another 20 minutes then season and serve.