In a medium bowl, combine the apples, lemon juice, white sugar and cinnamon. Stir to combine and let sit while you prepare the muffin batter.

Mix the gluten-free flour, brown sugar, granulated sugar, and cinnamon together in a small bowl. Stir in the melted butter, and then gently mix in the flour using a fork. Keep the mixture as large crumbles and do not over-mix. If over-mixed, this will turn into a thick paste. Set topping aside.

Preheat the oven to 425F. Line a standard muffin pan with paper baking cups.

In a medium bowl, whisk together the dry ingredients. Set aside.

In the bowl of a stand mixer fitted with a paddle attachment, add the eggs and brown sugar. Beat together until the mixture is light and fluffy, about 3 minutes.

With the mixer running on low, slowly drizzle in the oil. (Do this slowly so you keep the air you mixed into the eggs/sugar.)

With the mixer running on low, add ⅓ of the flour mixture followed by ½ of the yogurt. Mix until combined then add another ⅓ of the flour mixture. Add the rest of the yogurt and mix until combined. Then add the rest of the flour and mix until incorporated. Scrape down the sides and bottom of the mixer and mix for another 15-20 seconds until the batter is totally smooth.

Stir in the apple mixture with a rubber spatula until combined. Using a kitchen scoop or large spoon, portion the batter evenly into the prepared muffin tin. Sprinkle the crumb topping evenly over the top of the muffins. (If you want extra tall muffin tops you can refrigerate the muffins in the pan for 15 minutes before baking.)

Bake the muffins for 10 minutes, then turn down the heat to 375F. Continue to bake for another 10-15 minutes, until the muffins are lightly browned on top and a toothpick inserted into the center comes out clean.

Let the muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely. Enjoy!