Preheat the oven to 350 degrees F. Grease a 11 by 7 by 2-inch rectangular pan with the teaspoon of butter. In a saucepan, combine the raspberries, 1/2 cup of the sugar and lemon juice. Bring the mixture to a boil and reduce to a simmer. Simmer the mixture for 3 minutes. In a small bowl, whisk the water and cornstarch together. Stir the slurry into the fruit mixture. Cook and stir the mixture for 4 minutes. Remove the pan and cool completely. In the bowl of an electric mixer, fitted with a paddle, cream 8 tablespoons of butter and 1 cup of the sugar. Add the eggs, one at a time. In a small mixing bowl, sift 3 1/2 cups flour, baking powder, baking soda, salt and cinnamon together. Add the flour mixture and buttermilk, alternately to the butter mixture. Mix thoroughly. Mix in the vanilla. In a small bowl, combine the remaining butter, remaining flour and brown sugar together. Using your hands, combine the mixture until it resembles a fine crumb-like consistency. Spread half of the batter into the prepared pan. Spread the fruit mixture over the batter. Drop heaping spoonfuls of the remaining batter over the fruit mixture, about 1 inch apart. Sprinkle the crumb mixture over the entire pan. Bake for 40 to 45 minutes or until golden brown. In a mixing bowl, whisk the powdered sugar, maple syrup and milk together. Set aside. Remove from the oven and drizzle the frosting over the top. Cut into slices and serve warm.