• Preheat your oven to 220°C/200°C fan/gas mark 7.
• Chop the butter into small cubes (refrigerate if it's beginning to go soft). 
• Peel, quarter and core the apple. Cut the quarters into 1 cm cubes. 
• Halve the nectarine and remove the pit. Chop into 1 cm cubes.
• Bash or roughly chop the hazelnuts.

• Place a pan over medium-high heat with a knob of butter.
• Cook the apple and nectarine along with half the cinnamon and 1 tsp sugar until the fruit is lightly caramelised, 6-8 mins.
• Meanwhile, in a bowl, mix hazelnuts, flour, remaining sugar, a pinch of salt and as much of the remaining cinnamon as you like.
• Add the butter and use your fingertips to mix together until you have a crumbly texture that clumps together when pressed, 2-3 mins.

• Arrange the fruit in an appropriately-sized oven dish.
• Sprinkle an even layer of crumble over the top. 
• Bake until the crumble is golden and the fruit is tender, 30-40 mins.
• Allow to cool slightly before serving.

TIP: If the topping browns too quickly, cover the baking dish with aluminium foil.