Place the oven rack to the lowest position and preheat oven to 350°F.
Grease 9-inch glass pie plate with softened butter.
Sprinkle the grated Parmesan evenly into the bottom and up the sides of the buttered pie plate. Set aside.
In a large mixing bowl combine the grated Gruyere cheese, asparagus, and scallions.
Sprinkle the asparagus mixture in the bottom of the prepared pie plate.
In the now-empty bowl, whisk together the flour, baking powder, salt and pepper.
Add the half-and-half, eggs, mustard and melted butter and whisk until combined.
Slowly pour the egg mixture over the asparagus and cheese. Sprinkle the Sriracha seasoning on top.
Bake until the pie is light golden brown and the filling is set, about 30 minutes.
Allow the pie to rest for 15 minutes before serving. Cut into wedges and serve warm or at room temperature.
Notes
recipe adapted from The Best of American's Test Kitchen 2014Nutrition information is calculated using an ingredient database and should be considered an estimate. When multiple ingredient alternatives are given, the first listed is calculated for nutrition. Garnishes and optional ingredients are not included.