In a medium bowl; whisk together the oil, one cup of sugar, eggs, milk, and vanilla.
1/2 cup (120ml) vegetable oil, 1 cup (200g) granulated sugar, 2 large eggs, 3/4 cup (180ml) milk, 2 tsp vanilla extract
Add the wet ingredients to the dry ingredients, and gently stir using a rubber spatula until just combined. Fold in the chopped apples.
1 & 1/2 cups apples
Divide the batter into the 12 muffin cups. In a small bowl, mix together the cinnamon-sugar. Generously sprinkle on top of each muffin.
1/4 cup granulated sugar, 1 tsp cinnamon
Bake for 20-22 minutes or until a toothpick inserted into the center comes out clean.
Notes
Leftovers can be stored in an airtight container at room temperature for up to 3 days or in the fridge for up to 5 days. Please note that the cinnamon-sugar will lose its crispiness after a day from all the moisture in the muffin. You can reheat in a toaster oven or conventional oven at 350F for 10 minutes to warm and crisp up the muffins.
Substitutions:
AP flour - You can swap half of the AP flour with whole wheat pastry flour for a healthier alternative. You can also use self-raising flour, just omit the baking powder and salt. To make these muffins gluten-free, use Bob's Red Mill Gluten-Free 1:1 baking flour blend.
Baking powder - If you don't have baking powder, use 1 teaspoon of baking soda and 2 teaspoons of cream of tartar instead.
Vegetable oil - You can use the same amount of melted unsalted butter, avocado oil or any type of yellow oil like canola or safflower.
Eggs - The two eggs can be substituted with a 1/2 cup of unsweetened applesauce or 1/2 cup of mashed bananas.
Milk - You can use any kind of dairy or non-dairy milk.
Vegan option - Swap the eggs for applesauce and use non-dairy milk to make these muffins vegan.