1. Preheat oven to 450°. Sift flour into a large bowl. Cut cold butter into flour with a pastry blender or fork until mixture resembles coarse meal. Stir in thyme and rosemary.
2. Stir in crème fraîche, using a fork. Gradually stir in 3/4 cup buttermilk, adding up to 1/4 cup buttermilk, 1 Tbsp. at a time, to make a sticky dough. Gently stir with fork until dough pulls away from sides of bowl.
3. Turn dough out onto a floured (with self-rising soft-wheat flour) surface; sprinkle dough with flour, and pat to a 1-inch thickness.
4. Cut with a floured 2-inch round cutter, and place, with edges touching, in a greased (with butter) 9-inch square pan. Reshape and cut dough until all dough is used.
5. Bake at 450° for 15 minutes or until lightly browned. Serve immediately.
Note: These biscuits can easily be made ahead of time and frozen. Cook biscuits for 10 to 12 minutes or until they're just set but not browned. Remove from oven, cool completely on a wire rack, and place biscuits in a heavy-duty zip-top plastic freezer bag. Seal and freeze. To thaw, remove biscuits from bag, and arrange frozen biscuits on a baking sheet brushed with melted butter. Bake at 450° for 7 to 8 minutes or until thoroughly heated and lightly browned.