I've been making these crispy breakfast, brunch, lunch, and appetizer pizzas for several years in my baking classes. Try my topping selections and then make your own signature pizzas using your favorite ingredients. Garnish each pizza wedge with a small dollop of Crème Fraîche, if desired, just before serving.
Put the potatoes in a small saucepan, cover with water and add a little salt. Bring to a boil and cook until fork-tender. Drain, cool, and cut into 1/4-inch-thick slices. Set aside. Put the thyme, onions, bacon, and cheeses in separate small bowls and set aside.
Unwrap and unroll the thawed phyllo dough, placing the stack on a work surface. Put a 6-inch plate on top of the phyllo and cut around the plate and through the stack of dough with a small sharp paring knife. Continue cutting until all the dough is cut into circles. Discard the scrap dough and stack all the circles together. Lay a lightly dampened clean kitchen cloth over the top to keep the dough moist.
Preheat the oven to 400°F (205°C) and line two baking sheets with parchment paper or nonstick baking mats. Place three phyllo circles on each prepared baking sheet. Lightly brush all six circles with melted butter. Place another circle of dough on top of each of the first circles and brush again with melted butter. Continue until all six pizza circles are stacked with six layers of phyllo and butter. Put three to four slices of potato on top of each pizza stack. Sprinkle thyme, onions, and bacon over the potato slices, and top lightly with the two cheeses. Season to taste with pepper.
Bake until medium golden brown, making sure the centers and bottoms of each crust are also golden brown, 12 to 15 minutes. Transfer to a cutting board and cut each pizza into 4 wedges using a sharp chef's knife or pizza wheel. Serve immediately.
Note: Fingerling potatoes are one of the many varieties of new potatoes that have a creamy, moist texture. When buying fingerling potatoes, look for their small and distinct fingerlike shape. If you have a difficult time finding them, substitute another low-starch potato like Yukon gold or red new potatoes. The potatoes and bacon can be cooked ahead and stored in the refrigerator for up to 1 day.