1: Peel, cut into 4, then remove the core of 1 kg 500 g apple. Cut the quarters into slightly thick strips. Set aside.
2: In a large non-stick saucepan over medium heat, pour in 50 g butter and when melted, add 3 tablespoons maple syrup, 100 g brown sugar and 50 g whisky.
3: Bring to the boil, at which point you can flambé the whisky.
4: Pour in the apples and stir well. Cover, lower the heat and cook gently until the apples are just tender.
5: Butter a gratin dish and pour the apples into it.
6: Roast 50 g walnut kernels and 50 g flakeds almonds together in a small frying pan over medium heat, until the almonds are golden. Allow to cool. Preheat oven to 200°C (390°F).
7: Quickly chop the roasted walnut-almond mixture.
8: In a small bowl, pour in 250 g flour, 100 g rolled oats, 150 g butter, 100 g brown sugar and the walnut-almond mixture.
9: Mix by hand...
10: Until a coarse powder is obtained.
11: Pour over the apples.
12: Bake for 30 to 40 minutes at 200°C (390°F), until the top is golden brown.