Preheat oven to 350 F. Lightly spoon flour into dry measuring cups; level with a knife. Combine flour, sugar, and salt into a bowl: cut in butter with a pastry blender or fingers, until mixture resembles coarse meal. Reserve 1/2 cup flour mixture for topping; set aside.
Combine remaining flour mixture, minced rosemary, baking powder, and baking soda; add buttermilk, lemon juice, and egg. Beat at medium speed of mixer until blended. Spoon batter into an 8-inch cake pan coated with cooking spray. Combine reserved 1/2 cup flour mixture, lemon rind, and water; stir with a fork. Sprinkle crumb mixture over batter. Bake at 350 for 30 minutes. Cool on a wire rack. Garnish with rosemary sprigs and lemon slices if desired.
Yield: 8 servings.
For Lavender cake omit rosemary and lemon juice and add 2 t. lavender and 2 T buttermilk
When doubling recipe, bake in 9 X 13 Pyrex baking dish.
Bon appetite!