Grown-ups' Skillet Pizza: Crème Fraîche, Kale, Mushroom and Mozzarella

Directions

1. To make the dough: In a large bowl, whisk together the flour, salt, and instant yeast. Add the water. Using a rubber spatula, mix until the water is absorbed and the ingredients form a sticky dough ball. (If you need to use active dry yeast instead, proof it in the lukewarm water with a pinch of sugar first for about 10 minutes, until foamy, before adding to the other ingredients.)
2. Cover the bowl with a damp tea towel or plastic wrap and set aside in a warm spot to rise for 1 to 1 1/2 hours, until the dough has doubled in bulk. Note: Here's a trick for making the perfect warm spot for the dough to rise. Set the oven to 400° F and let it preheat for 1 minute, then shut it off. The temperature will be between 80° F and 100° F. you should be able to place your hands (carefully) on the oven grates without burning them.
3. Set a rack in the middle of the oven and preheat it to 550° F. Cover a work surface or cutting board liberally with flour — use at least 1/4 cup and more as needed. The dough is very wet, so don't hesitate to use flour as needed. Using two forks, deflate the dough by releasing it from the sides of the bowl and pulling it toward the center. Rotate the bowl quarter turns as you deflate, turning the mass into a rough ball. Turn the dough out onto your floured surface and use a bench scraper to divide the dough into 6 equal portions. With floured hands, roll each portion into a ball, using the pinkie-edges of your hands to pinch the dough underneath each ball. Let the balls sit on their tucked-in edges for at least 20 minutes without touching.
4. Meanwhile, prepare the kale-and-mushroom filling. Heat a large sauté pan over high heat. Add 2 tablespoons of the oil. When it shimmers, reduce the heat to medium, add the mushrooms and let them cook for 1 minute without disturbing them. After the 1 minute, stir to distribute and rearrange, then let cook for another minute. Stir again. Season with kosher salt and let cook another minute. When mushrooms are brown on all sides, scoop them into a bowl and return the skillet to high heat. Add the remaining tablespoon of olive oil. When it shimmers, add the kale and let cook for 1 minute without disturbing it. After the 1 minute, stir to distribute and rearrange, then let cook for another minute. Stir again. Season with kosher salt and let cook another minute. When the kale has wilted, turn off the heat, return the mushrooms to the pan, stir to combine, and taste. Adjust with salt to taste.
5. Pour 1/2 teaspoon extra-virgin olive oil into one or two 8- to 10-inch oven-safe skillet. (If you have two skillets, prepare two—I don't bake more than two pizzas at a time, but if you have two ovens or if your oven is large enough to fit three skillets on one rack, you can prepare three skillets at this step.) Transfer one ball of dough to each prepared skillet, and roll in the oil to coat.
6. With oiled hands and working from the center out, gently stretch the dough to fit the skillet or into an 8- to 9-inch round. As soon as the dough begins resisting or tearing, stop, let it rest for 5 minutes, then stretch again—small tears are fine and can easily be pinched back together.
7. Spoon crème fraîche over the dough leaving a 1/2-inch border or so—I use about a tablespoon per pizza. Top with a layer of sautéed kale and mushrooms. Top with mozzarella to taste. Drizzle lightly with olive oil. Sprinkle with sea salt. Place the skillets in the oven, one or two at a time, and bake for 8 to 10 minutes, until the edges are golden. Check the underside with a metal spatula; it should be crisp and golden brown. If the underside of the crust is still pale, continue baking for 3 to 5 minutes, or place the pan over a burner on medium-high heat for about a minute, keeping an eye on it the entire time and continuing to peek at the underside.