Add lemon juice, sweetener, and almond 1 cup milk to a blender, and blend to combined, (or you could add everything to a large bowl and whisk until everything is combined). Pour lemon mixture into an ice cube tray, and freeze at least four hours, (or overnight), or until frozen.
Just before serving, place lemon ice cubes in blender along with the additional 1 cup almond milk and frozen whipped topping. Blend until thick and creamy! *Note: If you desire a thicker lemonade, you could add ice cubes, or additional frozen whipped topping. (You could also add 1/4 tsp xanthan gum, which is also my secret weapon for thick and creamy shakes). If you want your lemonade a bit more slushy, add more almond milk according to desired taste!
*Quick Prep Method: * Put everything directly into a blender and blend until mixed together. Add ice cubes until desired ‘frosty’ consistency is reached. Enjoy!