1kg sweet potatoes, peeled
250ml grated Gruyére cheese
250ml grated cheddar cheese
2 cloves garlic, minced
375ml cream
15ml thyme leaves, chopped
1ml ground nutmeg
Preheat your oven to 180℃ and spray a ceramic dish with cooking spray. Set aside.
Slice the sweet potatoes into very thin slices – not thicker than 2mm.
Arrange the slices in a single layer overlapping slightly, in the oven dish.
Mix the two cheeses together and sprinkle a quarter of the cheese on the sweet potato. Keep going with the layers until you have a quarter of the cheese left. Set aside.
Add some vegetable oil to a saucepan set over medium heat. Add the garlic and cook while stirring, for about 1 minute.
Pour in the cream, thyme and nutmeg and simmer the mixture for about 5 minutes. It should thicken slightly.
Add the last quarter of the cheese to the saucepan and stir through until melted.
Season the cream with salt and pepper and pour it over the sweet potatoes.
Place the dish in the oven and bake until golden brown and bubbly – about 45minutes. Check that it is fully cooked by inserting a sharp knife in the centre.
Remove the gratin from the oven, rest for 15 minutes and serve.
My Whisk and I 