The biggest mistake people make with purees in simply not cooking the main ingredient long enough in the first place. Sweet potatoes can be boiled on the stovetop in water and such but I want to make this simple. Bake, scoop and mix. That's my favorite way. I am always surprised at what a sleeper this can be. I only add a little milk here to thin it out: I find cream and milk can dilute the sweet potato flavor. It also makes a great soup whisked into hot milk and blended…
Bake the sweet potatoes: Place the sweet potatoes in a single layer on 2 baking sheets. Put the trays in the center of the oven and bake until completely yielding when pierced with the tip of a knife, 1 hour to 1 1/2 hours.
Make the brown butter: In a medium saucepan, melt the butter completely over medium heat. Wait until it starts to simmer and turn golden brown, 3 to 5 minutes. Remove from the heat and stir in the brown sugar, molasses, dry ginger, fresh ginger, cinnamon and cloves. Set aside.
Make the puree: When the potatoes are cooked, place them on a flat surface and cut them in half. Use a large spoon to scoop out the flesh. Discard the skins and run the potatoes through the food mill. Transfer to a large bowl and season with salt and pepper. Stir in the milk and all of the reserved brown butter mixture. Taste for seasoning.
Finish and serve: Add a few "grates" of orange zest and then cut the orange and half and squeeze in the juice. Taste for seasoning. If the puree lacks sweetness, add a little molasses. If it lacks salt, add more salt or a splash Worcestershire Sauce.