Preheat oven to 350 degrees. Line a baking pan with foil or parchment paper. Cut the spaghetti squash down the middle (top to bottom) and scoop out/discard the seeds and center. Drizzle and brush with 1 tbsp olive oil, sprinkle with salt and pepper. Place both halves flat side down, rounded/back part up on the baking sheet. Pierce a couple times with a fork. Bake for 45 min.
While squash is baking, brown the ground beef in a large skillet. Drain grease and set the ground beef to the side in a bowl. Wipe any excess grease from the pan and heat 1 tbsp olive oil. Sauté green peppers and jalapeño peppers for a couple minutes. Add garlic, tomatoes and corn. Simmer on low about 10 minutes until vegetables are soft.
Return the ground beef to the pepper/tomato mixture. Add the black beans, cilantro, and seasonings. Stir to combine.
When the squash is done, use a fork to gently pull away the squash, creating a pile of “spaghetti” inside each half of the squash. Top with the southwest beef mixture. Add shredded cheddar cheese on top if desired and bake under broiler for a couple minutes until cheese is melted. Drizzle with sour cream and chopped green onion if desired.
