Peel the potatoes and cut them into large chunks. Place them in a pot of water and bring to a boil. Cook until fork-tender, then drain well.
If using a food mill or ricer, process the potatoes into a large bowl. If using a masher, mash until smooth, taking care to eliminate lumps. Stir in the vegan cream cheese, vegan butter, plant-based milk, garlic, poultry seasoning, and salt until well combined and creamy. Set aside.
Press the tofu dry and crumble it into small pieces.
Heat the olive oil in a large pan over medium-high heat. After 90 seconds, when the oil is hot, add the crumbled tofu and cook for 8-10 minutes, stirring occasionally, until lightly browned.
In a cup or small bowl, using the tines of a fork, whisk together the nutritional yeast, smoked paprika, tomato paste, molasses, bouillon paste, tamari, and water.
Add the marinade to the pan and continue to cook for 5-6 minutes until the tofu is evenly brown and slightly caramelized. Transfer the tofu mixture to a bowl and set aside.
In the same pan, melt the vegan butter over medium heat. When the butter is melted and bubbling, add the onion and mushrooms and sauté for 6-7 minutes until the mushrooms are tender and the onions are lightly golden.
Add the carrots, celery, garlic, peas, sage, oregano, and thyme, and continue to sauté for 3-4 minutes until the garlic is fragrant.
Return the tofu mixture to the pan. Pour in the red wine and simmer until reduced by half.
In a small bowl, whisk the cornstarch with water and tamari, then stir into the filling. Cook for 3-4 minutes until the mixture thickens, then remove it from the heat.
Preheat the oven to 400°F (205°C). Spread the filling evenly in a baking dish.
Spoon the mashed potatoes over the top, smoothing them into an even layer.
Use a fork to score the surface. Bake until the top is golden and lightly crisp, 28-30 minutes.
Let the shepherd’s pie rest for 10 minutes before serving. Spoon onto plates and top with vegan gravy, chives, parsley, and fresh sage.