Preheat oven to 400°F. Slice each sweet potato down the center, lengthwise. Smear a bit of olive oil on a rimmed baking sheet pan and place the sweet potatoes cut-side down on the sheet pan. Roast 40 minutes, or until they give when you squeeze them. Remove from oven and let cool.
Preheat oven to 375° F. Butter a baking dish that holds about 6 cups. Scrape the flesh from the sweet potato skins into a food processor or stand mixer with paddle attachment. Add the cream, butter, and salt and mix until smooth.
Scoop into buttered baking dish and smooth top with a spatula. Top with pecans, maple syrup, and butter pieces, cover with foil and bake for 15 minutes. Remove foil and bake 15 additional minutes, until potatoes are hot and pecans are crunchy.