Preheat oven to 350 degrees.
Make alfredo sauce: Melt butter in a medium saucepan over medium heat. Stir in flour and continue stirring until combined and creamy. Add cream and stir as it thickens. Slowly stir in garlic powder and parmesan cheese. Reduce heat to lowest setting.
Make potatoes: Heat olive oil in a small saute pan over medium high heat. Add potato slices and cook until lightly browned and cooked through the middle when pierced with fork.
Assemble pizzas: Place about 1-2 tbsp of alfredo on each Naan flatbread. Place a single layer of potato over alfredo. Sprinkle ¼ cup of each cheese over potatoes. Layer ¼ of the chanterelles on top of cheese. Sprinkle thyme leaves over chanterelles. Bake on lowest rack in oven to get a nice crispy crust until cheese is melted.In a medium bowl, quickly toss together arugula and dressing. Remove pizza from oven and top with about ½ cup of the salad. Enjoy!