Preheat oven to 350°F and lightly coat an 8×8-inch baking pan with nonstick cooking spray.
In a food processor, pulse rolled oats, butter, almond butter, ½ cup flour, 2 tablespoons Splenda Sweetener and ½ teaspoon kosher salt until mixture is crumbly. Set aside.
In a large bowl, whisk together remaining tablespoon of flour, 1 tablespoon sweetener, ½ teaspoon kosher salt. Add strawberries, blueberries, raspberries, and vanilla extract. Toss to combine.
Transfer fruit to prepared baking dish and top with reserved topping mixture. Bake for 40 to 45 minutes, or until bubbling and golden brown. Let cool at least 20 minutes before serving with non-fat whipped topping.