Coat an 8-inch square baking dish with cooking spray; set aside.
Whisk together SPLENDA® Granulated Sweetener, flour, cinnamon, apple juice, lemon juice, and lemon zest in a medium bowl; set aside.
Melt butter in a large nonstick skillet over medium-high heat; add apples and cook, stirring often, until softened, 8 minutes. Stir in apple juice mixture and bring to a boil; stir in raisins, if desired. Spoon apple mixture into prepared baking dish.
Combine flour, SPLENDA® Granulated Sweetener, baking powder, baking soda, and salt in the bowl of a food processor; add butter and pulse until mixture resembles coarse meal.
Transfer mixture to a medium bowl; stir in the sour cream, milk, and vanilla. Drop dough by spoonfuls onto the apple mixture; bake 25 minutes or until topping is lightly browned.