Microwave whole squash on High 5 minutes to soften. When just cool enough to handle, cut lengthwise in half and scoop out seeds. Place, cut side down in a shallow microwave-safe dish and microwave on High until flesh is completely softened, about 8 to 10 minutes. Let stand until cool enough to handle, about 15 minutes. Using a fork, pull squash from skin in long strands; set aside.
While squash is cooling, heat 1 tbsp oil in a large nonstick skillet over medium high heat. Add meatballs and turn to coat. Reduce heat to medium and cook, turning occasionally, until browned and cooked through, about 15 minutes. Transfer meatballs to a saucepan and add sauce (reserve skillet); cook over medium-low heat until heated through about 2 minutes.
Wipe skillet clean, add remaining 1 tbsp oil and heat over medium heat. Add garlic and cook 1 minute. Toss in squash and sauce and cook 2 minutes; add salt and pepper to taste.
On a serving platter, mound squash, top with meatballs and sauce, then sprinkle with parsley and cheese.
In a large bowl, using hands, mix together all ingredients until combined well. Using 1 tbsp mixture for each, roll into balls. (Can be made ahead: Transfer to a baking sheet and freeze until solid, about 1 hour. Divide between two heavy-duty resealable plastic bags, seal and freeze up to 3 weeks. Let stand at room temperature 10 min before cooking.)
Nutrition is for 1 meatball and 1 tablespoon squash.Cooking tips: I suggest you cook the squash in the microwave for a few minutes to soften the skin. This makes it much easier to cut it in half. Then simply scrape the seeds out, season and cook. This trick works for any hard, tough-skinned squash.Try my other meatballs recipes: