Preheat the oven to 375 degrees F.
Mix together the berries, flour and sugar and pour into a 8 by 8-inch baking dish. Spread the creme fraiche over the top of the berries evenly. Mix together the brown sugar, flour and salt. Mix in the melted butter. Top the creme fraiche with this mixture. Place in the oven and bake for 25 minutes, or until the topping is golden brown.