Heat the oven to 200C/180C fan/gas 6. Cover the cherries with boiling water and set aside for 10 mins. Meanwhile, mix the chia seeds with 3 tbsp warm water.
Drain the cherries and put in a large bowl with the soaked chia and the remaining ingredients, except the hazelnuts. Tip into a 2-litre ovenproof dish and scatter over the hazelnuts, then bake for 25-30 mins until piping hot in the middle. Serve with yogurt and cherry compote, if you like.