Prep: Preheat the oven to 350F and set a 9×13” casserole dish aside. In the meantime, add the lentils, rice blend, and vegetable broth to a small pot and bring to a boil over high heat. Cover once boiling, then reduce the heat to medium-low and simmer for 45 minutes. This can be done up to 3 days ahead of time, if you would like to plan ahead.
Roast the Squash: Cut each acorn squash in half and use a spoon to scoop out and discard the seeds. Use a knife to carefully score the squash, then place each half cut-side-up in the baking dish. Fill the bottom of the baking tray with 1/2” water, which will help steam the squash in the oven. Brush each squash with olive oil and a sprinkle of salt, then place in the oven to bake for 40 minutes.
Prep the Filling: Warm 1 tablespoon of olive oil in a pan over medium heat. Add the shallot and sauté for 3 minutes, until translucent. Then, add in the celery, garlic, and thyme. Sauté for an additional minute, then add in the mushrooms and tamari and sauté for 3 to 5 minutes. Finally, add in the cranberries and lentil/rice mixture; cook down for 1 to 2 minutes, until most of the liquid has evaporated from the pan.
Roast: Once the squash have cooked, remove from the oven and increase the temperature to 375F. Evenly divide the lentil “stuffing” among each squash, then return to the oven to bake for an additional 20 to 25 minutes, until the squash is golden and tender.
Serve: Serve warm, topped with pumpkin seeds and black pepper and thyme, if desired. Leftovers will keep in the refrigerator for up to 5 days, and can be reheated in the microwave, oven, or toaster oven.