Put the melted butter and the sugar in a big bowl and mix with a whisk.
Add the eggs and the sour cream and continue to mix.
In a separate bowl, add all the dry ingredients (that is, spices, soda and flour), mix them together and add them gradually to the other bowl.
Butter a bundt pan and pour the dough into the pan.
Bake at 180° C for 35 minutes (to be sure, try with a toothpick to be sure that the cake is ready: if the toothpick will come out without any dough attached to it, the cake is ready).
Let the cake cool down in the pan, remove from the pan and eventually level out the bottom of the cake in case it's not even.
To decorate, make a white icing by mixing the powder sugar and the water and pour onto the bundt cake.
Recipe by The Adagio Blog at https://adagioblog.com/spiced-bundt-cake/