1. Preheat the oven to 350 degrees and grease a 9x13 baking dish with nonstick cooking spray. 2. Beat together the butter, brown sugar, and molasses until smooth. 3. Add the ground cinnamon, nutmeg, cloves, and salt and mix to combine. Beat in the eggs and vanilla extract until well combined. 4. Add the evaporated milk and beat until mixed. 5. Fold in the sweet potatoes. 6. Spread the mixture in the prepared pan and bake in the oven for one hour, until the top of the casserole is golden brown.