Preheat the oven to 450°F. Wash and dry the fresh produce. Halve, peel, and thinly slice the shallot(s). Thinly slice the mushrooms. Thinly slice the chives. In a bowl, combine the béchamel, mozzarella (tearing into small pieces before adding), and as much of the red pepper flakes as you'd like, depending on how spicy you'd like the dish to be. Season with salt and pepper.

Transfer the pizza crust(s) to the center of 1 sheet pan (or 2 sheet pans for 4 servings); drizzle or brush with olive oil to evenly coat. Bake 6 to 10 minutes, or until lightly browned. Leaving the oven on, remove from the oven. Let cool about 5 minutes.

Meanwhile, in a medium nonstick pan (or large for 4 servings), heat a drizzle of olive oil on medium-high until hot. Add the sliced mushrooms in an even layer. Cook, without stirring, 3 to 4 minutes, or until lightly browned. Add the sliced shallot(s). Cook, stirring occasionally, 2 to 3 minutes, or until slightly softened. Add as much of the truffle zest as you'd like; season with salt and pepper. Cook, stirring occasionally, 1 to 2 minutes, or until the vegetables are coated and softened. Turn off the heat.

Leaving a 1-inch border around the edges, evenly top the baked crust(s) with the creamy mozzarella mixture, cooked vegetables, and a drizzle of olive oil. Bake 5 to 9 minutes, or until the cheese is melted and the crust is crispy. Remove from the oven and let stand at least 2 minutes. Carefully transfer the baked pizza(s) to a cutting board. Evenly top with the sliced chives. Cut into equal-sized pieces. Enjoy!