Step 1

Preheat the oven to 350°F. Lightly grease a 9x13-inch baking pan.

Step 2

Whisk together flour, baking powder, baking soda, and cinnamon in a large bowl, set aside.

Step 3

Using a stand mixer, beat together sugar and oil. Add eggs, one at a time, beating well after each addition.

Step 4

Add flour mixture and mix on low speed until well just combined.

Step 5

Fold in sweet potatoes and pecans - reserving a few pecans to sprinkle on the top at the end.

Step 6

Pour the batter into prepared pan. Bake for 50 to 60 minutes, or until a toothpick inserted in the center of the cake comes out clean. Cool completely before frosting.

Step 7

Using a stand mixer, beat butter until smooth.

Step 8

Add marshmallow cream and mix until combined.

Step 9

Add the powdered sugar and a pinch of salt and mix until combined.

Step 10

Spread the buttercream on the cooled cake and top with remaining pecans and a dash of cinnamon.