Sprinkle baking sheet with some cornmeal and set aside. Cut the ball of pasta dough into 8 equal pieces. Shape each piece into a rectangle about the size of a deck of cards. Corver the dought with plastic wrap while you are working. Roll a rectanle of dought through the widest setting of a pasta machine 3 times, until it is smooth. Continue rolling it through, decreasing in setting each time until you have reached the thinnest setting. Sprinkle the sheet light with cornmeal, gently fold it and set it on the cornmeal-lined baking sheet. Cover with plastic wrap. Continue rolling out the rest of teh pasta until all 8 pieces have been rolled out.
In a medium bowl, mix together the drained cream corn, mascarpone cheese, goat cheese, taraagon and pepper. Stir to combine and set aside. In a small bowl, beat the egg with 1 Tbsp water.
To form the agnolotti, place a sheet of pasta on a dry work surface. Using a pastry brush, brished the entire sheet of fresh pasta with egg wash. Place rounded teaspoons (abotu 1 oz) of corn filling on the pasta sheet, about 2 inches apart. Carefully places another sheet of pasta over the mounds, smoothing out any air pockets and firmly sealing the pasta around the filling. Using a scalloped pasta cutter (or a sharp knife), cut the pasta into small squares. Transfer the agnolotti to the cornmeal-lined baking sheet. Continue forming the remaining agnolotti.
To serve, bring a large pot of salted water to a boil over high heat. Add the pasta and cook until they float, about 2 minutes. While the pasta cooks, gently mix together all the tarragon butter ingredients in a medium serving bowl. Drain the pasta, using a large mess strainer or slotted spoon, and stranger them to the serving bowl with the tarragon butter. Toss to coat. Sprinkle with the Parmesan cheese and serve immediately.