Preheat the oven to 350°F. Spritz a loaf pan with nonstick baking spray (or butter and flour), then line it with parchment paper. Set aside.
Measure the sugar into a large bowl. Zest the orange directly on top of it, and mix until the sugar has the texture of wet sand. This will help the oils in the zest soak into the sugar and really sing in the cake.
Measure the coconut oil and applesauce into the bowl with the sugar mixture. Cream together with a hand mixer or a whisk.
Add the eggs, orange juice and orange zest. Mix until incorporated. Set aside.
In a separate bowl, measure the flour, baking powder and salt. Whisk until combined.
Sprinkle the dry ingredients into the wet ingredients, and stir using a rubber spatula until the batter just comes together.
Pour the batter into the prepared loaf pan, and transfer to the preheated oven.
Bake for 50-60 minutes, or until the top of the cake has browned and an inserted toothpick comes out clean.
Remove from the oven, and let cool completely on a wire rack.
While the cake cools, measure the ingredients for the frosting in a small bowl, whisking to combine.
Once the cake is at room temperature, drizzle the glaze over it, and serve immediately.