In a small bowl, mix together the orange juice, zest, and sugar and mix well until combined.
After baking, while the cake is still warm, remove it from the pan, and use a skewer to poke holes all over the surface. Place a sheet of baking paper under the cooling rack to catch any glaze that drips off the cake. Then pour the glaze onto the cake.
Next, put a second sheet of baking paper next to the cooling rack. Move the cooling rack with the cake onto a fresh sheet of baking paper. Using the first sheet of paper, pour any excess glaze back onto the cake, and repeat this step if necessary.
After glazing the cake, set it aside so the glaze can set and the cake can cool completely. Once set, the juice in the glaze will soak into the cake, and the sugar will create a crispy coating.
For Icing Glaze
In a small bowl, mix together the orange juice, zest, butter and sugar and mix well until combined and smooth.
If the icing is not pourable, you can microwave it for 30 seconds or so. If not thick enough add more sugar a little at a time until it reaches the desired consistency.