Preheat oven to 375 degrees.
Peel yams until they are sized for three or four bites each and the same size for even cooking. Save the peelings for another use.
Place the yams in a large saucepan, cover with water. Salt water liberally and bring to boil. Parboil yams for 5 minutes or until knife pierces with slight resistance. Potatoes will not be cooked completely but will finish cooking in the oven.
Drain and cool.
Meanwhile, in small bowl, combine cheese, herbs, garlic, salt, and pepper. Mash with a fork until fully incorporated.
Taste and adjust seasonings.
Set aside.
Wrap each stuffed yam tightly with thinly sliced prosciutto, working carefully so the prosciutto doesn’t rip.
Place the poppers on a sheet pan lined with aluminum foil and drizzle with oil.
Cook poppers for 10 minutes, then turn 1/4.
Cook for another 15 minutes, turning 1/4 again.
Repeat until all sides are crisp, browned, and easily pierced with fork.
Serve warm.