Prep the oven and pan: Preheat to 325°F (160°C). Grease and flour a 10-inch Bundt pan.
Mix dry ingredients: In a medium bowl, whisk flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Set aside.
Cream butter and sugar: Beat softened butter and sugar for 4–5 minutes until light and fluffy.
Add wet ingredients: Beat in eggs one at a time. Mix in mashed sweet potato, sour cream, Southern Comfort, and vanilla until smooth.
Combine wet and dry: Gradually mix in dry ingredients on low speed until just combined—don’t overmix.
Bake the cake: Pour batter into the pan and smooth the top. Bake for 60–70 minutes, or until a toothpick comes out clean. Cool in pan 15 minutes, then invert onto a rack to cool completely.
Make the glaze: Whisk powdered sugar and Southern Comfort until smooth. Add cream 1 tsp at a time if needed for a pourable consistency.
Glaze and serve: Drizzle glaze over the cooled cake. Let it set before slicing and serving.