In a large saucepan, combine the milk, water, pumpkin and a large pinch of salt. Set over medium hight heat and bring to a simmer. Slowly whisk in the cornmeal and lower the heat. Cook, stirring often, until the grits are tender and have thickened, 20-25 minutes.
In the meantime, set a large skillet over medium heat with the oil. Once hot, add in the sausage and use a wooden spoon to break it up. Cook until crispy and browned, about 5 to 8 minutes. Add in the butternut squash and cook until just beginning to brown. Use a slotted spoon to transfer the mixture to a bowl or plate and set aside.
Add another drizzle of oil (if needed) and add in the mushrooms and shallots. Cook, stirring often, until softened and browned, 8 to 10 minutes. Season with a pinch of salt, pepper, fresh thyme and crushed red pepper flakes. Add in the cooked sausage and butternut squash and sprinkle in the scallions. Lower the flame and keep warm.
Finish the grits by add in a large pinch of salt, pepper, the granulated onion, granulated garlic, dried oregano, dried thyme, chili powder, paprika, butter, and gouda. Stir until evenly combined and creamy. If they're too stiff, you can loosen with a splash of warm water.
To serve, divide the grits among serving bowls. Spoon over the sausage mixture and top with pepitas and parsley. Enjoy!