This loaded quiche is packed with all the flavors of classic chicken cordon blue: chicken, ham and Swiss cheese. A brush of Dijon mustard right on the crust add a bit of sharpness to cut through the richness of the egg custard.
Put a rimmed baking sheet in the middle of the oven; preheat to 425˚ F. Spread the mustard on the bottom of the pie shell. Layer with the chicken, ham, scallion whites and cheese. Whisk the half-and-half, eggs, 1/2 teaspoon salt and a few grinds of pepper in a small bowl; pour over the filling in the pie shell. Gently stir the top of the mixture to make sure the filling is covered; sprinkle with the scallion greens.
Carefully set the pie pan on the hot baking sheet. Bake until the filling is set, about 30 minutes.
When the quiche is almost done, thinly slice the cucumber and toss with the arugula, vinegar and a pinch each of salt and pepper. Serve the quiche with the salad.