Bring a large pot of salted water to a rolling boil.
Add the spaghetti and cook until al dente, according to package instructions.
Drain and set aside.
In a large skillet, melt butter and olive oil over medium heat.
Add minced garlic and sauté for about one minute until fragrant.
Season shrimp with salt, pepper, and Cajun seasoning.
Add shrimp to the skillet and cook for 1-2 minutes per side until opaque.
Remove shrimp and set aside.
Pour the heavy cream into the skillet and bring to a simmer while stirring.
Gradually add grated Parmesan, stirring until the sauce thickens.
Return shrimp to the skillet and add the pasta.
Toss everything together to coat well with the sauce.
Finish with a squeeze of lemon juice and adjust seasoning if needed.