Step 1: Preheat Oven : Preheat oven to 400°F (200°C).
Step 2: Prepare the Squash : Cut the spaghetti squash in half lengthwise and scoop out the seeds. Brush the cut sides with olive oil and season with salt and pepper. Place squash halves cut-side down on a baking sheet lined with parchment paper. Roast for 30–35 minutes, until the flesh is tender and easily pierced with a fork.
Step 3: Scrape the Squash : Remove squash from the oven and let cool slightly. Using a fork, scrape the flesh into spaghetti-like strands and set aside in a bowl.
Step 4: Cook the Shrimp : In a large skillet, melt butter over medium heat. Add garlic and sauté for 30–60 seconds until fragrant. Add shrimp and red pepper flakes (if using) and cook for 2–3 minutes per side until shrimp are pink and opaque. Add lemon juice, parsley, salt, and pepper; toss to coat.
Step 5: Combine Shrimp and Squash : Add roasted spaghetti squash strands to the skillet and gently toss with shrimp and garlic butter sauce. Adjust seasoning to taste.
Step 6: Serve : Spoon the shrimp and squash mixture back into the roasted squash halves for a visually stunning presentation. Garnish with additional parsley or a lemon wedge if desired.