Preheat your oven to 400 degrees F. Scrub the potatoes under cold water, and pat them dry with a paper towel.

Place the potatoes on a baking sheet. Use a fork to pierce the potatoes all over. Brush the outsides of the sweet potatoes with olive oil.

Bake for 1 hour to 1 hour and 15 minutes until a knife slides through with no resistance. Remove the baking sheet from the oven and let the potatoes cool for 10 minutes.

While the potatoes cool, make the butter. In a medium mixing bowl, beat the butter, brown sugar, cinnamon, vanilla, and salt together with a hand mixer for 2 minutes until smooth and fluffy.

Slice the potatoes down the center, fluff the insides with a fork, and top with some of the whipped cinnamon butter. Serve warm.