Prep and roast the squash: Preheat your oven to 400°F (200°C). Halve the spaghetti squash lengthwise and scoop out the seeds. Rub the cut sides with 1 tablespoon olive oil and season with salt and pepper. Place cut-side down on a parchment-lined baking sheet and roast for 35–45 minutes, until the strands pull apart easily with a fork and are just tender, not mushy.

Pat the shrimp dry: While the squash roasts, pat the shrimp very dry with paper towels. Season with salt, pepper, and a pinch of red pepper flakes. Dry shrimp sear better and stay juicy.

Start the garlic butter: In a large skillet, heat 1 tablespoon olive oil and 2 tablespoons butter over medium heat. When the butter foams, add the minced garlic and cook 30–60 seconds until fragrant, stirring constantly. Do not brown the garlic.

Cook the shrimp: Add the shrimp in a single layer. Cook 1–2 minutes per side until just opaque and pink. Transfer shrimp to a plate to prevent overcooking. Keep the garlicky butter in the pan.

Deglaze and brighten: Reduce heat to low. Add lemon zest and 1–2 tablespoons lemon juice to the pan. If the pan looks dry, add the remaining 2 tablespoons butter. Swirl until melted and silky. Taste and adjust salt, pepper, and lemon.

Shred the squash: When the squash is cool enough to handle, use a fork to scrape out the strands into a large bowl. Season with a pinch of salt and a drizzle of olive oil to keep it glossy.

Toss it all together: Add the squash strands to the skillet with the garlic butter. Toss to coat evenly over low heat. Stir in Parmesan and parsley. If using spinach or tomatoes, add them now and cook 1–2 minutes until just wilted or warmed.

Return the shrimp: Add the shrimp back to the pan and toss gently. Warm through for about 30 seconds. Finish with an extra squeeze of lemon and a pinch of red pepper flakes for heat.

Serve: Plate with extra Parmesan and a drizzle of good olive oil. Taste one last time and adjust seasoning. Serve hot.