Preheat oven to 350 degrees F. Grease and flour a 10” tube or bundt pan, and set aside.
In the bowl of an electric mixer with a paddle attachment, cream butter and then add the sugar, beating at low speed until light and fluffy, about 3-4 minutes. Add eggs, one at a time, beating after each addition at low speed until just incorporated. Scrape down the bowl after each addition. Add the buttermilk and beat just until incorporated. Batter will look lumpy.
In a separate bowl, combine flour, salt, baking powder, baking soda, and spices. Slowly add the flour mixture to the potato mixture at low speed until combined. Beat in the mashed sweet potatoes and vanilla.
Pour the batter into the prepared tube/bundt pan and level uniformly. Bake for 55-70 minutes or until a toothpick inserted comes out clean.
Cool on a wire rack for 20 minutes, then invert onto a serving plate. Once cake has cooled completely, prepare the caramel frosting if desired. Our sweet potato pound cake can be served plain, or topped with the Caramel Frosting.
For the Caramel Frosting: Bring brown sugar, heavy cream, and butter to a boil in a small stainless steel saucepan over medium heat, whisking constantly. Boil, whisking constantly for about 1 minute. Remove pan from the heat and stir in vanilla. Gradually whisk in powdered sugar until smooth. Continue to stir mixture until it just begins to cool and thicken. Immediately pour mixture over cooled sweet potato pound cake and let set. Decorate sides with fresh cranberries and mint leaves, or as desired.