1/2 cup buttermilk you could use 1/2 cup regular milk/cream/nut/soy milk + 1/2 teaspoon vinegar to mimic buttermilk if you don’t keep buttermilk on hand
1/2 cup coconut flakes I used Tropical Traditions unsweetened shredded coconut. They are unsweetened and very fine flakes. If using Baker’s or grocery-store brand shredded coconut, increase to 3/4 cup