Preheat the oven to 170°c. Butter and flour the forms well.
Grate the rind off the orange. Place approx. half of the sugar into a bowl. Rub the orange rind into the sugar between your thumbs and index/middle fingers until it starts to smell like orange candy.
Add the butter to the bowl and beat on high for a couple of minutes until the butter and sugar form a creamy mixture.
Add the salt and eggs and beat on high for 2-3 minutes until fluffy.
Sift the flour and baking powder into a separate bowl to combine. Add the flour mix into the rest of the batter in three parts and mix well between each addition and at the end.
Place approximately 1 1/2 tablespoons of batter into each form and smooth the top with the back of the spoon. Bake for 15 minutes or until a tester inserted into a cake comes out clean.
Remove the cakes from the oven and allow them to cool for a couple of minutes before removing them from the forms.
For the glaze
Juice the orange. Pour the remaining sugar into the juice and stir. The aim is not to dissolve the sugar, but to make a sort of “glaze”.
Pour the glaze over the cakes. The juice will soak into the cake while the sugar will leave little crystals on the top of each cake.
To ensure that your Gugelhüpfe don't stick to the forms, make sure you butter the forms very well and dust them with flour. Remove the Gugelhüpfe from the forms as soon as they have cooled enough to do so.