In a small saucepan over medium heat, whisk together Splenda, water, cinnamon and vanilla until well blended, about 1 minute. Stir in milk and continue to heat over medium heat, stirring until steaming, about 2 minutes. Remove from heat. Transfer to a blender and process for 20 seconds until foamy. If you don’t have a blender, don’t worry about it. Just whisk the mixture continuously with a wire whisk until foamy.