Preheat Oven to 400°F.
Place the squash, cut side down, on a sheet tray lined with parchment paper.
Roast for 30 min. flip the squash over, then continue roasting until tender about 20 more minutes. Remove from oven and set aside.
In the meantime, heat a medium pot to medium heat and add quinoa. Pour in vegetable stock and 1 tsp. of salt and stir. Bring mixture to a very low simmer, cover, and cook for 20 minutes or until the liquid has evaporated and the quinoa is tender.
Remove from heat and let sit in the pot for 6 minutes. Fluff with a fork and set aside.
Heat a large sauté pan to medium-high heat, add ¼ cup of water (or 1 tbsp. of oil) and cook the mushrooms until golden brown, about 6-7 minutes. If the mushrooms begin to stick, add a little bit of vegetable stock.
Lower heat to medium-low, and add shallots, cook for 3-4 minutes or until the shallots are tender.
Mix in the greens, and let them cook down, about 1-2 minutes.
Add the mushroom mixture to the quinoa in the pot, and mix well. Season to taste.
10. Fill your acorn halves with the quinoa mixture and top with the pipian rojo, and chopped cilantro. Place plenty of extra pipian rojo on the table, because you will be coming back for more of this delicious sauce!