Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan. You can use butter or nonstick spray. For extra insurance, line the pan with parchment paper and leave some overhang for easy lifting.

In a large mixing bowl, cream together the softened butter and sugar until light and fluffy. This can take about three to five minutes with an electric mixer. The mixture should look pale and airy.

Add the eggs one at a time, mixing well after each addition. This gradual method helps the batter stay smooth instead of separating.

Stir in the mashed sweet potatoes and vanilla extract until well combined. The batter will look slightly orange and smell wonderful.

In another bowl, whisk together the flour, baking powder, baking soda, cinnamon, nutmeg, and salt. Whisking eliminates clumps and distributes the leavening agents evenly.

Gradually add the dry ingredients to the wet mixture, alternating with the buttermilk. Start and end with the flour mixture, mixing until just combined. Avoid overmixing at this stage.

Pour the batter into the prepared baking pan and smooth the top with a spatula. The batter will be thick but spreadable.

Bake for 30 to 35 minutes, or until a toothpick inserted in the center comes out clean. Start checking at the 30-minute mark because every oven runs a little differently.

Allow the cake to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely. Cooling in the pan helps the structure set.

Serve plain or with a dollop of whipped cream for an extra treat.