Preheat the oven to 400°F (200°C).
Arrange lemon slices in a single layer on a sheet pan. Place the shrimp and asparagus on top of the lemon slices. Sprinkle with Italian seasoning, red pepper flakes, salt, pepper, parsley, and minced garlic.
Distribute the butter slices evenly over the shrimp and asparagus.
Bake for 10-15 minutes, or until the shrimp are pink and the asparagus is tender.
Toss everything in the melted butter to coat.
Adjust seasoning if needed, then squeeze fresh lemon juice over the top.
Serve with rice or pasta for a complete meal.