Cut off the top 1/3 inch of each pepper, remove and discard the seeds. If needed, cut a small amount of the bottom off each pepper so that they sit flat. Season the insides evenly with 1/4 teaspoon salt. Nestle the peppers inside an 8-inch baking dish and set aside.
Heat a large skillet over medium-high heat. Add the oil and heat another minute. Add the plant-based meat and use the back of a wooden spoon to break apart the meat into small pieces. Cook, stirring occasionally, until the meat is browned, about 5 minutes. Add the shallots, fennel, oregano and 1 teaspoon salt and cook another 4 minutes or until fragrant and the vegetables begin to soften. Stir in the rice, tomatoes, spinach, Parmigiano-Reggiano cheese, basil and pepper and cook until the spinach is wilts and the cheese is melted. Divide the mixture among the peppers. Top with the Provolone piccante. Add 1/2 cup of water to the bottom of the pan. Bake the peppers for 40 minutes or until the cheese is melted and peppers are soft but not falling apart. Serve hot.