Preheat your oven to 350°F (175°C). Grease and line a loaf pan with parchment paper.
Cook the sweet potato by roasting it, boiling it, or microwaving it until soft. Once cooked, mash it until smooth and measure 1 cup.
In a large bowl, mix the mashed sweet potato, grated apple, eggs, honey, oil or butter, milk, and vanilla extract. Stir until well combined.
To your bowl, add the flour, baking powder, baking soda, cinnamon, and salt. Mix until just combined.
Bake: Pour the batter into the prepared load pan and spread it out evenly. Bake for 50-60 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cake to cool in the pan for 10 minutes before transferring it to a wire rack to cool completely. Slice and serve!