If using frozen shrimp, thaw completely and drain excess water. Pat dry with paper towels.

Peel fresh shell-on shrimp and reserve shells for broth if desired.

Combine broth, fish sauce, soy sauce, cinnamon stick, star anise, sliced ginger, and shrimp shells in a saucepan; bring to a simmer.

Chop cilantro leaves; add stems to broth. Simmer for 20-25 minutes, then strain solids and retain the broth.

Meanwhile, boil water in a wide skillet; add rice noodles and soak for 3-5 minutes according to package instructions. Drain and set aside.

Add mushrooms and broccoli to broth; cook for 4-5 minutes until tender but crisp.

Add shrimp to the broth; cook for 1-2 minutes until pink and firm.

Divide noodles into bowls; ladle hot broth and shrimp mixture over noodles. Garnish with sliced jalapenos, lime wedges, and cilantro leaves.