Preheat the oven to 375 degrees Fahrenheit. Grease or place liners in a 12 cup muffin pan and set aside.
In a medium bowl, whisk together gluten-free flour blend, xanthan gum (if using), baking powder, baking soda, salt, and ground cinnamon. Set aside.
In a separate bowl, mix together vegetable oil, applesauce, granulated sugar, brown sugar, unsweetened almond milk, apple cider vinegar, and vanilla extract until smooth.
Add the dry ingredients to the wet ingredients. Stir until combined.
Stir in chopped apples.
Evenly spoon mixture into muffin cups.
To make the cinnamon topping, in a small bowl mix together brown sugar, gluten-free flour blend and cinnamon.
With your hands, work in the cold butter until the mixture is the size of small peas.
Sprinkle streusel topping evenly over the muffins.
Bake at 375F for 18-22 minutes or until a toothpick inserted in the middle of a muffin comes out clean.
Cool in muffin pan for 5 minutes before moving to a cooling rack.