50g flour (gluten free works)
2 cloves garlic
1 tsp dried tarragon
4 cups milk
800g potatoes (I used Agria)
3 granny smith apples
70g cheddar cheese
Preheat oven to 180 degrees
Finely slice the onion and finely chop the garlic. Heat a pot on a moderate heat, add the butter and then cook the onion and the garlic until softened without colouring. Add the tarragon.
Add the flour and continue to cook for one minute. Whisk in the milk 1 cup at a time, allowing it to thicken each time before adding the next.
Peel and slice the potatoes about 2mm thick (I like to use a mandolin or a food processor if possible). Wash, quarter and remove the core from the apples (leaving the skin on is fine) and then slice the same thickness as the potatoes
Place a layer of the potato in the bottom of a baking dish approx. 20 x 30 cm. Lightly season with salt and pepper and then add a layer of the apples. Pour over 1/3 of the sauce and continue this process until you layered all of the potato and apple, finishing with a layer of the sauce.
Grate the cheddar and sprinkle over the top of the gratin. Cover with foil and bake in the oven for 1 ½ hours or until the potato is tender. Remove the foil and continue to cook for another 5-10 minutes to brown the top of the gratin
Enjoy as a side dish with a main meal.