Method:
Preheat oven to 400°F. Melt 4 tablespoons butter with rosemary and thyme. Set aside to infuse.
In the bowl of a food processor, pulse both flours with the sugar, baking powder, salt and soda. Dice remaining butter and add it to the flour. Pulse until mixture resembles coarse crumbs. Transfer mixture to a mixing bowl. (Alternatively, stir the ingredients together in a large mixing bowl. Using a pastry blender cut the butter into the flour mixture.) Stir in the sage leaves followed by the buttermilk.
Line a baking sheet with parchment paper. Drop tablespoons of dough onto the sheet in 12 even mounds. Brush the tops with the herb butter, and if desired, sprinkle with a little sea salt.
Bake the biscuits until golden brown and fragrant, 15 to 20 minutes. Cool on a wire rack for a minute or two before serving.