Step 1Bring a pot of water to a rolling boil and, using a pair of tongs or rubber gloves, add the nettles to the pot. Blanch the nettles for about 1 minute. Drain, coarsely chop and reserve.
Step 2In a heavy-bottomed medium pot, bring 5 1/2 cups of water to a boil. Add the salt and olive oil, then slowly pour in the polenta, stirring constantly with a wooden spoon.
Step 3Reduce the heat to medium-low so the polenta cooks at a low simmer (bubbling slightly). Stir frequently until thick and creamy, about 17 to 20 minutes.
Step 4Add the Parmigiano-Reggiano, creme fraiche and nettles, whisking until combined. Taste for seasoning and serve immediately.