Preheat oven to 375°F. Halve squash lengthwise and scoop out seeds. Place squash, cut-side down, on a large baking sheet and prick skin all over with a fork. Bake until tender, about 45 minutes.
After squash has cooked for 35 minutes, warm oil in a large nonstick skillet over medium-low heat. Add kielbasa, garlic and cumin. Cook until fragrant, about 2 minutes; set aside until squash is done.
Remove squash from oven and scrape flesh into skillet using a fork (will resemble spaghetti strands); toss until evenly coated. Season to taste with salt and pepper; serve. Yields about 3/4 cup per serving.