Preheat oven to 375°F and line a baking sheet with foil.
Prick the sweet potatoes all over with a fork, place on the sheet and bake for 1 hour and 15 minutes. Remove from the oven and let them cool for 15 minutes.
Once the sweet potatoes have cooled, slice in half, and scoop out the orange flesh into a bowl. Mash with a potato masher or a fork.
Finely chop the chipotle chiles, and stir into the mashed sweet potatoes along the butter and salt. When well combined, taste and add more salt if desired. Serve warm.
Notes
This is 1 or 2 peppers (depending on how hot you want it), not full cans!