Line medium bowl with several layers of paper towels. Spoon ricotta cheese into bowl. Let drain at least 30 minutes and up to 1 hour.
Beat egg, 1/3 cup Pecarino Romano cheese, salt, and white pepper in large bowl to blend. Mix in ricotta. Sprinkle 3/4 cup flour over and stir gently to blend. Cover and chill dough 1 hour.
Line rimmed baking sheet with plastic wrap. Place some flour in bowl. For each gnudi gently roll 1 heaping teaspoonful of dough into ball. Add to flour; toss to coat lightly, shaping into short log. Place on baking sheet.
Cook gnudi in large pot of boiling, salted water until very tender, about 8 minutes.