You can skip using the food processor and just mash potatoes with a fork or potato masher, but they are especially creamy when you food process them.
Preheat oven to 300°F.
Wash unpeeled sweet potatoes well, then use a fork to make a series of punctures all around. Place sweet potatoes on a foil- lined baking sheet and roast in the oven until soft when poked with a fork (about 2 hours).
Meanwhile, melt butter in a medium saucepan over medium- low heat until fragrant. Whisk in maple syrup and thyme.
Peel sweet potatoes. Discard (compost!) the peels, then put the sweet potato flesh into a food processor. Add the butter-maple mixture and puree, drizzling in the olive oil with the motor running. Process until smooth and creamy.
Rewarm if needed and season with salt and freshly ground black pepper to taste.