Beat together eggs and sugar until creamy and pale yellow.
In the same bowl, add buttermilk, baking soda, melted butter, and mashed sweet potato. Stir until mixed.
Add flour, cinnamon, and ginger to a small bowl and stir lightly.
Add flour mixture to wet ingredients and stir with a wooden spoon until mixed.
Pour into a well-seasoned 9-inch cast iron pan. You can use a greased and floured 8-inch square pan instead.
Bake at 350 degrees for 30 minutes or until a toothpick inserted in the center comes out clean.
Remove from oven and prepare icing.
Cook butter, brown sugar, buttermilk, and salt in a small pan over medium heat, stirring constantly, until the butter and sugar have melted. Add coconut and pecans and continue stirring until the mixture reaches a medium rolling boil.
Immediately, pour icing on top of warm skillet cake and spread across entire surface.
Place under broiler for 2 to 3 minutes or until browned. Do no get distracted. Once the topping starts to brown, you've got a few seconds that separates browned from burned.
Remove from oven and completely cool on a cooling rack before cutting.