Bring the water and salt to a boil in a large pot. Add the pasta and cook according to the package directions until just al dente.
Drain the pasta and rinse it under cold running water for about 2 minutes to stop the cooking.
While the pasta cooks and drains, get the cheese sauce prepared. Crumble the drained tofu and add it to a blender pitcher or food processor along with the garlic, onion, pumpkin puree, tapioca starch, plant milk, apple cider vinegar, olive oil, nutritional yeast, smoked paprika, Dijon mustard, and white miso. Blend for 90 seconds on high speed until completely smooth. Stop and scrape down the sides of the pitcher once or twice during the blending to make sure everything get’s mixed in.
Transfer the cheese sauce to a large saucepan and cook over medium heat, stirring constantly. After 4-6 minutes, the sauce will begin to thicken. Continue cooking for 2–3 minutes, stirring continuously, until smooth and bubbling.
Heat the olive oil in a large skillet over medium heat. Add the chopped vegan bacon (seitan bacon is my personal top choice for this) and cook for 3-4 minutes, stirring occasionally, until lightly browned all over.
Add the sage to the cooking seitan and sauté for 30-45 seconds just to wilt the leaves. Remove from the heat.
Add the drained pasta and cooked vegan bacon mixture to the sauce and stir until evenly coated. If the sauce is too thick, add some additional unsweetened plat based milk a few tablespoons at a time until the desired consistency is reached.
Preheat the oven to 400°F (200°C). Transfer the macaroni and cheese to a baking dish and spread into an even layer.
Sprinkle the panko breadcrumbs and uncooked vegan bacon over the top. Drizzle with olive oil and bake for 15–20 minutes, until the topping is crisp and the edges are bubbling.
Garnish with the sage leaves and chives before serving.