Preheat the oven to 350F and line a 12 cup muffin pan with liners, making sure to spray the inside of liners with cooking spray.
In a large mixing bowl, combine almond flour, baking soda, salt, and sweetener. Next add your eggs, greek yogurt, vanilla extract, and lemon zest. Stir well. Last, fold in your blueberries.
Scoop your batter into the muffins cups evenly using a scoop or spoon. Set aside.
In a small mixing bowl, combine all your ingredients to make your crumble topping. The crumble will be powdery.
Using a spoon, divide your crumble evenly on top of each muffin. Place into already preheated oven and bake for 18-20 minutes or until toothpick comes out clean. Let cool and serve.