Heat oven to 400.
Grease muffin pan or line with paper cups.
Mix topping ingredients together, cutting in the butter with a pastry cutter or a fork until its crumbly. Set aside.
Toss blueberries with 1 tablespoon of flour to coat.
Mix dry ingredients in a large bowl. Combine the creme fraiche, milk, oil, egg and extract together. Pour the wet mixture into the dry, stir, add the lemon juice and continue to mix until the dough comes together. Fold in the blueberries.
Spoon the batter into the prepared muffin tin, sprinkle with topping and bake in preheated oven for 20-25 minutes or until a tooth pick comes out clean.