In a large pot, bring salted water to a rolling boil. Add spaghetti and cook until al dente, usually about 8–10 minutes. Reserve ½ cup of pasta water before draining.

In a mixing bowl, combine shrimp with 2 teaspoons of Old Bay seasoning and lemon juice. Toss until well-coated and let sit for 5 minutes.

Heat a skillet over medium-high heat. Add 1 tablespoon of butter and olive oil. Once melted, add ½ tablespoon of garlic and sauté for 30 seconds. Add shrimp and cook for 2–3 minutes per side until pink and opaque. Remove shrimp and set aside.

In the same skillet, lower heat to medium and melt remaining butter. Add shallots and sauté for 2 minutes until translucent. Add remaining minced garlic and sauté for another 30 seconds. Pour in white wine, deglaze, and reduce for 1 minute.

Stir in heavy cream, remaining Old Bay seasoning, and Parmesan cheese. Cook for 2–3 minutes until the sauce is smooth and creamy.

Add cooked shrimp and parsley back to the skillet. Stir in drained spaghetti and toss everything together for 1 minute. Adjust thickness with reserved pasta water if needed.

Serve immediately, garnished with additional Parmesan cheese and parsley.