Preheat the oven to 425 degrees F.
For the tomato sauce: In a large pot, heat the oil over medium-high heat. Add the garlic, carrots and onion and saute until the vegetables are soft, approximately 5 minutes. Season with salt and pepper. Add the tomato sauce and bring to a simmer. Cover and simmer on low heat until thick, about 20 minutes.
For the crust: Meanwhile, in a bowl, whisk together the chickpea flour, garlic powder, salt and 2/3 cup water. In a 7 1/2-inch round nonstick pan, heat the olive oil over medium heat and pour the "dough" into the pan (about 1/8 inch thick). Cook the "dough" until the edges start to brown, approximately 3 minutes. Flip the crust over like a pancake and cook on the other side for another 3 minutes. Transfer the crust to a baking sheet.
To finish the tomato sauce, put the sauce into a food processor and process until smooth.
For the pizza topping: Brush the olive oil over the chickpea crust. Spread a thin layer of the tomato sauce over the crust, leaving a 1/2-inch border. Sprinkle on the grated provolone, covering the tomato sauce. Place the chicken sausage slices on top.
Bake until the cheese is melted and bubbling, 10 to 15 minutes.