Pour water into a mixing bowl. Add vanilla and pancake mix; whisk until smooth.
Heat 1 tablespoon of butter in a large skillet over medium heat. Place one apple slice in the butter and pour about 1/4 cup of pancake mix over top, until it just covers the apple slice. Cook pancake until bubbles begin to form and edges dry out. Flip. Sprinkle with cinnamon and cook another minute or two.
When pan begins to dry, add remaining butter and melt in the skillet.