Preheat oven to 350° F. Line a muffin pan with muffin liners.
In a large mixing bowl, combine light brown sugar, vegetable oil, eggs, vanilla extract, and grated apple. Whisk to combine.
Add in all-purpose flour, baking powder, baking soda, salt, and cinnamon. Mix until just combined.
Add in milk and continue to mix until the batter is well incorporated.
Fold in the diced apple until well dispersed throughout the batter.
Portion into the muffin liners using a large cookie scoop (3 tablespoons).