Preheat oven to 350°F. Add prunes to a saucepan; cover with water and bring to a boil. Remove from heat and let stand for 10 minutes. Strain any excess water. Mash prunes and set aside. In a bowl, stir flour with cinnamon, cloves and nutmeg; set aside. In a separate bowl, beat sugar with eggs and butter until blended. In a measuring cup, mix prune juice with baking soda. Stir into mixture alternating with flour mixture. Stir in mashed prunes. Transfer to a 9x13 inch baking pan lined with parchment paper. Bake for 30 to 35 minutes or until tester inserted into center comes out clean. Cool for 15 minutes. Remove from pan and cool completely on rack. Meanwhile, prepare the sauce.
Add butter, sugar, syrup, cream and baking soda to a small saucepan set over medium heat; bring to a boil. Boil for 2 minutes. Cut cake and serve with warm sauce.