How to Make It
Make the Sweet Potato Cake: Preheat oven to 350˚F. Beat butter with an electric mixer on medium speed until creamy, about 2 minutes; gradually add sugar, beating well. Add eggs, 1 at a time, beating well after each addition. Add sweet potatoes; beat well.
Stir together flour, baking powder, salt, cinnamon, nutmeg, baking soda, and ground cloves a medium bowl. Add to butter mixture alternately with milk, beginning and ending with flour mixture. Beat well after each addition. Stir in chopped pecans. Spoon batter into a greased (with cooking spray) 9-inch square pan. Bake in preheated oven until a wooden pick inserted in center comes out clean, about 35 minutes. Cool completely, about 1 hour.
Make the Brown Sugar Icing: Melt butter in a medium saucepan over medium; add brown sugar. Let come to a boil, stirring constantly. Stir in heavy cream and vanilla; return to a boil. Remove from heat; transfer to a large heatproof bowl, and cool 45 minutes.
Add powdered sugar to cooled sugar mixture. Beat with an electric mixer on high speed until creamy and icing reaches a spreading consistency, 2 to 3 minutes.
Spread Brown Sugar Icing over cake. Cut into squares to serve.