I threw together a couple pizzas with stuff I had in the fridge, and this one made with mostly beet greens was so unexpectedly good, I had to write it down. The measurements below are all hand-wavy, but the most important thing is this: lots and lots of chopped beet greens (especially the stems!), piled raw on top of dough, drizzled with olive oil, and in to a very hot oven. —thzhou
Figure out your dough situation first. I used Kenji's recipe on Serious Eats (https://www.seriouseats.com/recipes/2013/01/foolproof-pan-pizza-recipe.html) this time around, but I often use Smitten Kitchen's lazy pizza dough (https://smittenkitchen.com/2013/10/lazy-pizza-dough-favorite-margarita-pizza/) too. Note that these will require you to get started a day in advance. You can also use store-bought dough.
On the day that you're making your pizza, pull out a 10 inch cast iron skillet, and pour a couple glugs of olive oil in to it. Plop in your half batch of pizza dough and flip it over to coat in olive oil. Then let it sit for 2 hours, until it's relaxed and spread out closer to the edges of the pan.
While you're waiting for your dough, prep the toppings by chopping the beet greens (you should end up with ~2 cups) and very thinly slicing the mushrooms. Tear apart the mozzarella in to small pieces. Heat oven to 550 degrees F, or as hot as it will go.
When your dough's done resting/rising (or when you're tired of waiting), use your fingers to push the dough the rest of the way to the sides of the pan. Pop any super big bubbles while you're at it. You can also pick up an edge of the dough to stretch it out before setting it back in the pan, and work your way around the sides that way. Because the dough's gonna be pretty thick all around, I don't bother leaving a lip around the edge.
Now you're ready to top. Take the tomatoes, crush it in your hands (try not to squirt juices everywhere), and spread the flesh and juices around on top of the pizza, all the way to the edge. Sprinkle with salt and black pepper, and some more olive oil if you feel like it.
Place down a layer of mozz, using up about 2/3 of prepped cheese.
Dump the beet greens on top in an even layer, and sprinkle with salt. Add the mushroom slices, if using. Top with the remaining mozzarella. Add one last drizzle of olive oil, making sure each mushroom gets a bit.
Bake for 12-15 minutes, until things are melty, sizzly, and well browned on top. If the bottom crust is a little pale (mine usually is), put the skillet on the stove over medium heat and brown it that way for a couple minutes. Top with crushed red pepper flakes, and serve.