Step 1

Preheat the oven to 350 degrees Fahrenheit. Add 12 muffin cups to a muffin tin.

Step 2

In a medium bowl, mix the 1 1/2 cups all-purpose flour, 1/2 cup rolled oats, and 2 teaspoons cinnamon with the ginger, allspice, baking powder, baking soda, and kosher salt.

Step 3

In another bowl, combine the maple syrup, applesauce, unsalted butter (melted), and vanilla.

Step 4

Mix the wet ingredients into the dry ingredients and stir until a smooth batter forms. Mix in the diced apple.

Step 5

In another medium bowl, add the remaining 1/4 cup rolled oats, 2 tablespoons flour, and 1 teaspoon cinnamon along with the turbinado sugar and salted butter (cut into small pieces). Cut the butter into the remaining ingredients using a pastry cutter or fork until it’s evenly combined and a crumbly streusel topping forms.

Step 6

Divide the batter evenly into the muffin cups. Then top with a thin layer of streusel.

Step 7

Bake for about 25 to 30 minutes, until a toothpick comes out clean (if your oven is uneven, reverse the pan halfway through). Allow to cool in the pan for 5 minutes, then remove the muffins and place them on a cooling rack to fully cool.