Preheat the oven to 350°F.
Arrange the yams on a baking sheet, drizzle with oil and salt. Roast until fork-tender, about 30 minutes.
Add all of the chipotle butter ingredients to a blender or food processor and blend until smooth.
To serve, slice an opening in the top of each yam, spread with chipotle butter and garnish with cheese and green onions.