Preheat the oven to 400°F (or 204°C).
Using a sharp knife, cut each acorn squash in half lengthwise (instructions here) and scoop out and discard the seeds. Arrange the squash halves on a large baking sheet, flesh-side up. Drizzle the flesh with the 1 tablespoon olive oil, and sprinkle generously with kosher salt and pepper and the thyme leaves. Bake the squash, flesh side down, for 40 minutes, or until tender.
Meanwhile, make the filling. Combine the cooked quinoa, lentils, pine nuts, olives, spices, 1/2 teaspoon kosher salt, lemon juice, tahini, and parsley. Stir well.
Allow the squash halves to cool slightly, then stuff each cavity with the quinoa filling. Drizzle each with extra tahini if desired.