Cut the apples and pears into small pieces and place them in the baking dish. Add the blueberries and mix with vanilla, lemon juice, cornstarch, salt and maple syrup.
Crumble
Put all ingredients in a mixing bowl and mix everything well.
Pour the crumble topping over the fruits and bake in the oven for 30 to 35 minutes until golden. The fruit juice should now be reduced and form bubbles on the edges while the crumble is firm.
Serving
Serve hot or cold with yogurt, cream or ice cream.
Can be stored up to 3 days in the refrigerator or up to 2 months in the freezer (provided the baking dish can be frozen). You can prepare and freeze a larger amount of crumble topping.