2 tablespoons extra-virgin olive oil, plus more as needed
3 small acorn squash, halved lengthwise and seeded
Fine sea salt to taste
Freshly ground black pepper to taste
4 medium-size shallots, cut into 1/2-inch/1.25 cm dice
8 ounces/225 g fresh shiitake mushrooms, stemmed and sliced thinly
1 tablespoon chopped fresh sage
6 cups/85 g spinach leaves
4 cups/450 g cooked millet
1/3 cup/45 g unsweetened and unsulfured raisins or dried currants
2 large organic, pasture-raised, or antibiotic-free eggs, lightly beaten
Preheat oven to 400°F/205°C. Arrange a rack in the upper half of the oven and another in the lower half. Oil two large, rimmed baking sheets.
Sprinkle the squash with salt and pepper. Arrange the squash, cut side down, on the prepared baking sheets and roast until tender, about 30 minutes.
Meanwhile, in a large skillet over medium-high heat, heat the oil. Add the shallots and cook, stirring occasionally, for 2 minutes. Add the mushrooms and sage and cook, stirring occasionally, until the vegetables are tender, 4 to 5 minutes. Working in batches, add the spinach, stirring until wilted before adding the next batch. Transfer the mixture to a large bowl.
Add the millet, raisins, and salt and pepper to taste. Stir in the eggs. Use this mixture to stuff the squash halves. Return the squash to the baking sheets and bake until the stuffing is heated through and browned on top, 20 to 30 minutes. Serve hot.