Preheat the oven to 350 degrees. Line a 12-muffin pan with paper or silicone liners. Blend the dry ingredients and orange zest in a medium bowl. In another bowl, beat the butter and sugar together until creamy, then add the eggs and beat until blended. Add the rest of the dry ingredients, and beat until combined. Add the dry ingredients to the wet mixture and blend gently with a spatula. Divide the batter evenly among the muffin pan. Smooth tops with the back of a wet spoon, and garnish the tops with 2-3 nut halves and a few sprinkles of toasted coconut. Bake for about 22-25 minutes, or until golden on the outside and a toothpick inserted into the center of a muffin comes out clean.