Cook pasta according to package directions; reserve ½ cup pasta cooking water before draining; set aside.
Steam the broccoli for 2 minutes until fork tender, and toss with the cooked pasta.
In a large pan, heat 1 tablespoon butter, season the shrimp with salt and pepper and add to the heated pan. Cook shrimp for 2-3 minutes per side until shrimp turns opaque and is fully cooked; toss with the cooked pasta and broccoli.
In the same pan, heat the remaining butter, add garlic and cook, stirring constantly, until fragrant, about 1 minute.
Add flour, then whisk to combine and cook for 1 additional minute. Slowly whisk in the milk, then cream cheese, then let the sauce simmer uncovered until thickened, about 2-3 minutes.
Pour the sauce over the pasta mixture and stir well. Add as much reserved pasta water for the desired sauce thickness.
Serve with freshly ground pepper and parmesan cheese, if desired.