Roast the hazelnut flakes in a pan without fat, remove and let cool. Squeeze the lemon and mix the juice with 3 tablespoons of sugar (or maple syrup) and 1/2 teaspoon of cinnamon.
Wash the grapes, pat dry, pluck from the stems and cut in half. Wash the pears, quarter them, remove the core and cut into thin wedges. Mix the grapes and pears with the lemon juice mixture.
Season the yogurt with 1 tablespoon of sugar (or maple syrup) and a little cinnamon. Divide the fruit between 4 dessert glasses and top with the yoghurt. Garnish with nuts and mint.