Preheat the oven to 550°F, or as hot as it will go. If you have a baking stone, place it in the oven on a rack in the bottom third of the oven. If you don't have a baking stone, place a baking sheet on the rack to heat with the oven. Heat the oven for at least 30 minutes before baking.
Roll out the dough and transfer it to a floured, rimless cookie sheet or a pizza peel, if you have one.
Spread a couple teaspoons of olive oil over the dough, then evenly scatter the white beans and garlic over top. Slice or pinch off pieces of the Taleggio and scatter them over the pizza, then grate a little Parmesan over the pizza.
Toss the spinach in a large bowl with a bit of olive oil, salt, and pepper, and set aside. (Because it's hard to slide a heavy pizza off a cookie sheet or peel, and because you're going to have a mound of loose spinach leaves that tend to fly off when you shake it, it's best to transfer the pizza to the hot stone or baking sheet before adding the spinach.)
Gently shuffle the pizza onto the baking stone or baking sheet. Pull out the oven rack (if you haven't already) and gently mound the spinach leaves in the center of the pizza. Close the oven and cook for 7 to 8 minutes, until the crust is brown on the edges and the spinach is wilted.