Preheat the oven to 325°F. Grease and flour a standard Bundt pan.
Whisk together the flour, baking soda, and 1 teaspoon of the cinnamon.
In the bowl of electric mixer fitted with paddle, beat the sugar, eggs, oil, vanilla, and orange juice until combined.
With mixer on low, add dry ingredients just until incorporated.
Fold in apples, walnuts, and coconut, then spoon batter into prepared pan and smooth the top.
Bake for 1 hour 15-20 min, or until a toothpick inserted in the center comes out clean.
Cool in pan for 15 min, then invert onto wire rack set over baking sheet.
Puncture the top all over with a skewer to create deep holes for the glaze to soak into.
For the glaze, combine the sugar, butter, baking soda, and buttermilk in a medium saucepan.
Cook over medium heat, stirring constantly, until mixture comes to a boil, about 4-5 min.
It should be foamy and begin to turn light brown.
Pour the hot glaze over the warm cake.
If desired, combine the confectioners’ sugar with the remaining ¼ teaspoon cinnamon and dust over the top.
Let cake rest for at least 1 hr before serving.
