Preheat the oven to 180°C, fan160°C, gas 4. Put the plums and apple in a 1 litre ovenproof dish and toss with the maple syrup and vanilla extract.
Make the crumble by placing the oats and coconut in a bowl, add the butter and sugar and mix everything together well.
Sprinkle the crumble over the fruit and cover with foil. Bake for 15 minutes, then remove the foil and bake for a further 10 minutes until cooked and golden and the fruit is softened and the topping crunchy.
Cook's tip: for baby, place a little of the cooked fruit in a blender with a little boiled water and blitz to make a purée. Stir through a little thick natural yogurt to serve.