Put 2 halved, seeded spaghetti squash in a microwave-safe bowl; add 1/4 cup water, cover and microwave 16 minutes. Let cool slightly, then scrape into strands with a fork. Heat 2 tablespoons olive oil in a skillet over medium heat. Add 2 tablespoons tomato paste, 1/2 teaspoon dried oregano and a pinch each of cinnamon and sugar; cook, stirring, 2 minutes. Add 1/2 cup water and bring to a simmer; season with salt. Add the squash and toss. Top with feta.