Preheat oven to 375 degrees F.
On a lightly floured surface, cut puff pastry into rounds using a 3 1/4" cookie cutter. Place each round into a regular-size 12-muffin tin. Bake for about 10-15 minutes or until lightly golden. Let cool! They will look like bread rolls. Once cooled, twist off the top of each carefully to make them into cupped tart shells. You can invert the twisted off tops and use them as additional tart shells if desired.
Meanwhile, place cream cheese, goat cheese, heavy cream, salt, pepper, sugar, and tarragon into the bowl of a stand mixer with a paddle attachment. Beat all together until obtaining a creamy, homogeneous mixture. Spoon into the tartlets and smooth with the back of a spoon.
Place beets onto a cutting board and cut each slice in half. Garnish Pickled Goat Cheese Tartlets as seen in the pictures or as desired (use the pickled beets, golden tomatoes, quartered boiled eggs, toasted pine nuts, and tarragon leaves or baby arugula). Enjoy!