How to Make It
Preheat oven to 350°.
Combine the raspberries and 1 tablespoon flour in a medium bowl; toss well.
Bring tomato, 1 cup granulated sugar, and water to a boil in a medium saucepan; cook 4 minutes. Remove from heat; stir in the raspberry mixture. Pour mixture into a 13 x 9-inch baking pan coated with cooking spray.
Lightly spoon 1 cup flour into a dry measuring cup, and level with a knife. Combine 1 cup flour, 1/3 cup granulated sugar, brown sugar, baking powder, and baking soda in a bowl, stirring with a whisk. Cut in the butter with a pastry blender or 2 knives until mixture resembles coarse meal. Add buttermilk, stirring just until moist. Drop the dough by heaping tablespoons onto fruit mixture. Bake at 350° for 50 minutes or until the filling is bubbly and crust is browned.