Preheat the oven to 400 F (205 C) for at least 30 minutes before baking. Line (2) 12 ct. muffin pans with cupcake liners.
Use a small knife or vegetable peeler to peel the apple. Core the apple or simply slice the apple into wedges. Finely dice the apples. Set aside for now.
1 cup apples, peeled, cored and finely diced
If you would like to top the apple oat muffins with the spiced oat topping, mix the flour, oats, brown sugar and cinnamon together until well combined. Pour the melted butter into the cinnamon oat mixture, mixing together with a fork until the butter is thoroughly mixed through. In another mixing bowl, whisk the flour, oats, baking powder, baking soda, cinnamon and salt together until well combined. Chill in the fridge while you make the muffin batter. ¼ cup (30 g) all purpose flour, ¼ cup (20 g) quick cooking oats, 2 tablespoons (25 g) light brown sugar, ½ teaspoon cinnamon , 2 tablespoons (28 g) melted unsalted butter
In another bowl whisk the oil, sugar, light brown sugar, eggs, applesauce, milk, apple cider and vanilla extract until smooth and well combined. Stir the dry ingredients into the wet. When about ¾ of the dry ingredients have been mixed into the wet, toss the apples into the muffin batter. Gently fold the apples into the muffin batter until just combined.
1½ cups (180 g) all purpose flour, 1 cup (80 g) quick cooking oats, 1½ teaspoons baking powder, ½ teaspoon baking soda, 1 teaspoon ground cinnamon , ½ teaspoon salt
For more bakery style muffins, alternate filled and unfilled muffin wells. Use a 3 tablespoon sized cookie scoop to scoop the apple and oatmeal muffin batter into each of the muffin liners, alternating every other cup. Top the muffins with the cinnamon oat topping or just a sprinkle of coarse sugar. 2 large eggs, room temperature, ½ cup (100 g) light brown sugar, ¼ cup (50 g) granulated sugar, ½ cup (120 g) unsweetened applesauce , ¼ cup (60 ml) apple cider or apple juice, ¼ cup (60 ml) milk, room temperature, ¼ cup (60 ml) neutral oil , 2 teaspoons (10 ml) vanilla extract
Bake the muffins at 400 F (205 C) for 18 - 20 minutes. The muffins are done when a toothpick inserted into the center comes about with a few moist crumbs or when a finger pressed gently into the center of the muffins quickly bounces back. Be careful as the topping will be very hot.
Cool the oat apple muffins in the muffin pan for 5 - 10 minutes. Carefully remove the muffins to cool to room temperature and enjoy.