for the streusel topping
1/4 cup butter, cold, cut into small cubes
1/2 cup flour
3 tablespoons unsweetened cocoa
4 tablespoons sugar
1/2 cup sweetened flakes coconut, toasted
for the muffins
1/2 cup butter, softened to room temperature
1 cup white sugar
1 cup buttermilk
1 3/4 cups all-purpose flour
1/2 cup unsweetened cocoa powder
1/2 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
1 cup mini semi-sweet chocolate chips (regular sized will work as well)
Preheat the oven to 350F. Line a standard muffin tin with liners.
If you have not already toasted the coconut, spread on a baking sheet and toast while the oven is heating up, 10-12 minutes, checking frequently as it goes from toasted to burned very quickly. Once toasted, let cool. To make the streusel topping, mix together flour, cocoa and sugar in a small bowl. Using a folk or your fingers, work the butter into the mixture until it looks like coarse sand. Add the cooled coconut.
In a large bowl, cream together the butter and sugar until light and fluffy. Beat in the eggs one at a time, then stir in the buttermilk. In a separate bowl, mix together flour, cocoa, baking powder, baking soda and salt; stir dry ingredients into the buttermilk mixture until moistened. Mix in chocolate chips. Fill muffin lines 2/3 full and sprinkle with topping.
Bake for 18-20 minutes, until a toothpick inserted near the center comes out clean. Cool in the pan for 15 minutes before removing to a wire rack to cool completely.