TANGLED LEEK’ZA
Position rack in lower third of oven. Place a pizza stone or overturned rimmed baking sheet on rack. Preheat oven to 500°F.
Thinly slice 4 inches of dark greens from 1 large leek (9 to 12 oz). Cut white and light-green parts of leek crosswise into 4-inch pieces, discarding the hairy root. Slice 4-inch pieces in half lengthwise, then thinly slice them.
In a small skillet, heat a few big glugs of extra-virgin olive oil over medium. Add leek greens and 3 cloves garlic, smashed and peeled; season with kosher salt and freshly ground black pepper. Cook 3-4 minutes or until softened and translucent (do not brown). Add ¾ cup heavy cream and 4 thyme sprigs; bring to a boil. Reduce heat to maintain a brisk simmer; cook, stirring, 4-5 minutes or until cream has reduced and slightly thickened. Remove from heat. Zest 1 lemon directly into pan (halve lemon and reserve for serving). Stir to combine; season with salt and pepper. Lightly smash the now-softened garlic cloves into the sauce. Transfer sauce from heat to cool, about 10 minutes.
In a small bowl, toss leeks and a few glugs of oil. Season with salt and pepper.
Generously dust a pizza peel or the back of an overturned large, rimmed baking sheet with semolina or fine cornmeal. With floured hands, stretch 1-lb room temperature dough into a 15 x 9-inch rectangle; place on peel. Give it a shake to make sure the dough isn’t sticking.
Remove and discard thyme sprigs from cream sauce. Spread sauce on dough in an even layer, leaving a 1-inch border. Rip 4 oz fresh whole-milk mozzarella cheese, thinly sliced, into ragged pieces; scatter over top of pizza, along with 4 oz fontina cheese, cubed. Dust with grated Parmigiano-Reggiano cheese. Top with leeks. Drizzle the whole pie, including crust, with oil; sprinkle on more Parmigiano (be careful not to get oil on the peel or baking sheet, or dough may stick). Slide dough onto preheated stone or baking sheet. Bake 16-20 minutes or until crust is blistered and leeks are frizzled and browned on the edges. If crust is browning more on one side than the other, rotate pan halfway through.
Remove pizza from oven; top with a drizzle of oil, a grating of Parm and lots of black pepper. Sprinkle with leaves stripped from 5 thyme sprigs. Let pizza cool before cutting and squeezing lemon halves over the top. Serves 4.