Preheat the oven to 500 degrees F. Place the pizza stone on the top rack of the oven. Slice the dates into 1/4" pieces. Set aside. Slice the prosciutto into 1/4" ribbons. Set aside. Slice the radicchio into 1/4" pieces. Set aside. Pull the leaves from the bunch of basil, slice, and add to the radicchio. Toss gently to combine.
If using store-bought pizza dough (For directions on making Chef Dan Kluger's pizza dough, see below.): Remove the pizza dough from the refrigerator and let it sit at room temperature for 2 hours to soften and temper. Gently stretch and pull the pizza dough on your fingertips into a 12 to 14" circle. Dust the pizza peel with a pinch of flour, and lay the dough on the peel.For the pizza dough (yields 6, 12" pizzas): In the bowl of a stand mixer, mix yeast, olive oil, salt, sugar, and water until combined. Add flour and using a dough hook attachment, mix until the dough comes together. Take dough out of the mixer and place in a container that has been greased with olive oil and cover tightly with plastic wrap. Leave at room temperature for at least 12 hours. Remove the dough from the container and separate into 7-ounce portions. Lightly fold and roll into loose balls. Place in floured containers, cover, and refrigerate until ready to use.
Dollop the ricotta cheese onto the prepared pizza dough. Sprinkle the fontina and parmesan cheeses over the ricotta. Scatter the dates over the cheese. Finish with a pinch of dried oregano. Slide the pizza onto the preheated pizza stone, and bake until pizza crust is crispy and golden on the bottom, rotating halfway through, about 5 to 7 minutes of total baking time, depending on the heat of your oven.
Using the peel, remove the pizza from the oven and let cool on a cutting board. Top with prosciutto and chili flakes. Dress the radicchio/basil mixture with balsamic vinegar and olive oil. Scatter over the pizza, slice, and serve immediately.