Preheat oven to 350. To make the muffins, combine flour, sugar, baking soda, and salt. In a separate bowl mix together buttermilk, butter, eggs, and vanilla. Stir wet ingredients into dry ingredients until just combined. Stir in orange zest. Fill greased muffin tins 2/3 full.
Prepare the streusel. Combine shredded coconut, butter, sugar, and flour in a small bowl. Mix to combine. Spoon onto muffin batter.
Bake 15-20 minutes or until an inserted toothpick comes out mostly clean. Allow to cool.
Prepare the glaze. Mix together powdered sugar and hot water. (Add extra water 1 teaspoon at a time until desired consistency is reached). Stir in coconut extract. Drizzle over muffins. Store in airtight container.
Notes
Store in airtight container at room temperature, or wrap individually and freeze.