Make crumble topping: combine all crumble topping ingredients in a bowl and mix well.
Pre-heat oven to 400 degrees F.
Mix berries, maple sugar, flour, and juice in a bowl. Divide the mixture into four 6-ounce ramekins, two 12-ounce ramekins, or one large ovenproof dish.
Top each ramekin with ¼ cup of Crumble Topping. Place dishes on a baking sheet.
Bake berry crumbles ~25 minutes, until golden brown and bubbling. Cool for 15 minutes before serving.
Garnish with dollop of yogurt or whipped cream and mint leaf (optional).