Heat oven to 425 degrees.
In a storage bag or tupperware, combine tempeh, oregano, garlic, basil, onion, thyme, rosemary, red pepper flakes, and salt and pepper. Pour 2 tbsp olive oil over to. Toss tempeh around in the bag and stow in the fridge at least 20 minutes.
Once oven preheats, poke holes in the sweet potatoes and roast for 45-60 minutes until tender. Remove to a safe surface and let cool.
While potatoes roast, prepare the filling. Warm a skillet on medium and toss in tempeh and spices. Cook, stirring ocassionally, until some of the tempeh begins to crisp. Remove from heat and let cool slightly, about 5 minutes.
To a small bowl, combine mozzarella, pesto, and tempeh. Taste for salt and pepper.
When the potatoes are cool enough to handle, slice in half. Remove most of the inner flesh, leaving about 14 inch space all around, and reserve for a later use. Spoon filling evenly into each sweet potato half. Top with shredded parmesan. Cook 10-15 minutes until crispy and cheese begins to bubble and turn golden.
Serve with fresh parsley and Greek yogurt. Plus, your favorite wine, of course.