Place 6 to 8 cups broth in a medium sauce pan and heat to a simmer; reduce heat and keep warm.
Cut the cauliflower into florets (cut off the bottom, then cut the head in half and remove the florets). Line a baking sheet with parchment paper, place the cauliflower in the pan and drizzle on 2 tablespoons olive oil, ½ teaspoon kosher salt, and fresh ground black pepper. Mix to thoroughly coat. Place in the oven and roast for 30 minutes, until tender and browned, stirring once.
Meanwhile, mince 1 shallot. Then, in a large heavy-bottomed skillet, pot, or Dutch oven, heat 2 1/2 tablespoons butter over medium high heat. Add the shallot and ½ teaspoon kosher salt, reduce heat to medium, and cook until translucent, stirring often, about 3 minutes. Add 1 1/2 cups rice and stir to combine, about 2 minutes. Increase heat to medium-high and add 3/4 cup white wine. Cook, stirring, until liquid is almost evaporated, a few minutes.
Add 1/2 cup warmed broth to skillet. Cook, stirring frequently, until the broth is almost absorbed. Repeat, gradually adding broth 1/2 cup at a time and stirring , until rice is tender but still al dente and sauce is creamy (you may not need all the broth). The process should take about 20 to 25 minutes.
Stir in the roasted cauliflower, 3/4 cup Parmesan cheese, 4 cups spinach leaves, and 1 cup cooked chickpeas. Continue to stir until the spinach is wilted (or turn off the heat and cover the dish for a few minutes). Remove from heat and season to taste with kosher salt and fresh ground black pepper. Serve immediately, garnished with additional Parmesan cheese.