Preheat oven to 375 degrees F (190 degrees C). Press pie crust into a 9-inch deep-dish pie plate.
Heat butter in a skillet over medium-high heat; add butter. Cook and stir asparagus in the melted butter, about 2 minutes. Add garlic; cook and stir until asparagus is tender, 2 to 3 minutes more. Remove skillet from heat, adding more butter to asparagus to taste.
Season salmon with salt and black pepper; cook with the asparagus over medium heat until fish flakes easily with a fork, about 4 minutes per side. Remove skillet from heat and chop salmon into small pieces.
Beat eggs and cream cheese together in a bowl until smooth; add half-and-half and stir.
Spoon salmon and asparagus into pie crust and pour in egg mixture, filling almost to the rim. Set pie plate on a baking sheet.
Place baking sheet on the lower rack in the preheated oven and cook until a knife inserted in the center comes out clean, 35 to 45 minutes. Let quiche set for 10 minutes before slicing.