Crustless Artichoke, Crab and Spinach Quiche with Gruyere

6 ounces crab meat (about 1 cup), back fin or lump
3/4 cup frozen artichoke hearts, thawed and chopped (may substitute canned or jarred)
1 cup lightly packed baby spinach, roughly chopped
3/4 cup shredded Gruyere cheese
8 large eggs
1/2 cup milk (I use nonfat; 2% or whole milk work well, too)
1/2 teaspoon Dijon mustard
1/2 teaspoon kosher salt
1/4 teaspoon pepper
Optional for pie plate: 1/2 tablespoon butter and 2 tablespoons Parmesan cheese

Preheat oven to 375 degrees and lightly grease a 9-inch pie plate. As an option, you may spread 1/2 tablespoon of butter over the plate then sprinkle with 2 tablespoons Parmesan to coat.
Scatter the crab, artichokes, spinach and cheese evenly in the pie plate.
In a large mixing bowl, whisk the remaining ingredients until well blended. Pour into pie plate. (You may need to gently work the egg mixture under the solid ingredients with a fork.)
Bake for 40 minutes or until just firm in the center. If the top begins to brown too much, cover lightly with a piece of foil. I typically cover for the last 10 minutes or so.
When cooked through, remove from oven and allow to rest for five minutes before serving.