A succulent creamy side dish that goes well with most meaty dishes or can be had on it's own with a side salad. I normally serve this with roast chicken.
Put the peeled and sliced potatoes in a deep pan and cover with water. Sprinkle some salt. Bring to the boil and stand by. As soon as the water boils, give it 20-30 seconds, then turn off the heat and drain out all the water and set the potatoes aside. The potato slices will look slightly transparent in appearance but not fully cooked. This is called blanching. It cuts down on the baking time later and helps ensure the potatoes suck up the lovely white sauce properly.
Next, you can begin preparing the white sauce. Melt butter in a saucepan, stir in plain flour, then cook on low heat for 5 minutes. Cooking the flour in the butter helps reduce the 'raw' smell of the flour so don't skip this step! Add the garlic, salt and pepper. Then slowly whisk in the milk. If you pour milk in too quickly you will form lumps, so add gradually while whisking briskly to get rid of any lumps and form a smooth roux/mixture. Then bring to a boil, while stirring. Turn down heat and cook until the sauce starts to thicken and coats the back of a wooden spoon. Add the cream and give it another final boil. Taste and adjust salt/pepper. Turn off the heat and set aside.
Butter a 9x11 pyrex dish, then pour a spoonful of the white sauce and spread it to cover the bottom of the dish. This bottom layer of sauce helps make sure your potatoes are yummy down to the last bite and prevents them from sticking to the bottom of the dish. Add half of the blanched potato slices. Now pour half of the white sauce. Sprinkle some red chilli flakes/chopped chillies and herbs. Layer the remainder of the potato slices followed by all remaining white sauce. Level everything up and sprinkly some more herbs if you like. Now scatter the grated cheese all over the top.
Preheat your oven at 180C. Bake the gratin uncovered for approx. 20-30 mins or until the top is golden and potatoes are tender.
Serve warm with accompaniments of your choice.