In a medium bowl, combine shrimp, 2 tablespoons of the olive oil, and blackening seasoning. Stir to evenly coat the shrimp. Set aside to use right away, or, for more heat, cover and refrigerate for up to 12 hours.

Bring a large pot of salted water to a boil. Cook pasta to al dente according to package directions. Drain and set aside.

While pasta cooks, warm remaining 1 tablespoon oil in a large skillet set over medium-high heat. Add shrimp and cook for 1-2 minutes per side, just until charred and cooked through. Remove cooked shrimp to a plate.

After removing the shrimp, melt butter in the same skillet, then whisk in flour and cook for 60 seconds.

Reduce heat to medium. Whisk in broth and lemon juice.

Add cream, garlic powder, salt, and pepper. Whisk until smooth, then let the sauce simmer for 1-2 minutes to thicken slightly.

Stir in Parmesan. Let it melt until the sauce smooths out once again. Taste and add more salt or pepper as desired. Stir in the pasta, toss well, top with cooked shrimp, and serve.