Preheat oven to 400℉. Prepare a muffin pan and set aside.
In a medium bowl, sift together 2 cups flour, 1 cup coconut sugar, ½ teaspoon baking powder, and ½ teaspoon salt. Set aside.
In a medium bowl, combine 2 eggs, ½ cup of melted butter, ½ cup milk, and 1 teaspoon of vanilla extract. Whisk until well combined (no clumps).
Slowly add in the dry ingredients. Fold in the fresh blueberries.
To prepare the streusel topping, add the ingredients into a medium sized bowl. Use a pastry cutter (or fork), to cut in cold butter until topping is crumbly and coarse. Stop mixing when you have pea-sized and larger crumbles.
Fill prepared muffin cups with batter. Top each muffin with streusel topping, about 1 tablespoon each. Bake until golden brown, about 20 to 22 minutes. Cool muffins on a rack for several minutes before removing from pan. Enjoy!