In a large mixer bowl, combine water, buttermilk, sugar, melted butter & yeast, stir & then allow to sit approx 15 minutes for yeast to proof. (you know it's ready when it's puffed & frothy)
Add in eggs, salt & flour & mix together slowly using a dough hook until flour is incorporated
Set on med-low speed & mix/knead 10 minutes
Once mixed, let rest 10 minutes while you make your filling & preheat the oven
Prepare the filling by combining brown sugar, sugar, cinnamon, nutmeg & ginger in a small bowl & mixing with a fork
Preheat oven to 375 degrees & line a baking sheet with a non-stick mat
Roll dough out on lightly floured surface into a flat & even layer (approx 12x15)
Brush melted butter over dough & then sprinkle filling mixture on top
Roll tightly on the long side & then cut into 12 large rolls (easiest way to make them even is to first cut the log in half & then cut those two pieces in half again & then those 4 pieces into thirds)
Place on prepared baking sheet & bake 15-20 minutes
Remove & allow to cool slightly while you mix your icing
Prepare the icing by combining all ingredients in a small bowl & whisking well until you reach desired consistency
Drizzle over the top of the rolls while they are still warm