Wash and rinse blueberries under water and set aside in a small bowl.
Preheat oven to 425°.
In a medium sized bowl, sift together flour. Measure ¼ C of the sifted flour and pour over blueberries. Gently stir to coat the blueberries in flour.
Take your remaining flour and add sugar, baking powder and salt. Then set this mixture aside.
In a medium size bowl, beat the egg using a whisk until light and fluffy. Add melted butter and whisk together with the egg. Continue to add coconut extract, buttermilk and sour cream and whisk everything together until smooth.
Slowly pour wet ingredients into the dry ingredients and use a wooden spoon to mix just until combined. Your batter will be thick, but careful not to over mix! Lastly, fold in the blueberries and shredded coconut.
To prepare streusel topping, combine butter with all dry ingredients. Use a pastry cutter or fork to cut the butter into the dry ingredients until no large chunks remain.
Grease your muffin pan with Crisco. I like to use Crisco instead of oil spray, but a spray works fine too.
Fill your muffin tin all the way to the top with batter. Add 1 tablespoon of streusel to the top of each muffin.
Bake for 5 minutes at 425° and then reduce heat to 350° and bake for another 16-20 minutes. Do not open the oven for at least 15 minutes, you will see how nicely the muffins rise. Baking times will vary by oven.
Check your muffins for doneness by inserting a toothpick into the center of the muffin. If your toothpick comes out clean, your muffin is done. Allow muffins to cool completely in the pan. You can also cool on a wire rack, but you want to allow them to cool enough to remove and transport them out of the pan.