To make sure that your that chicken Béchamel is tasty all the way from the topping to the sauce to the innermost part of the meat, season the dish during every stage of cooking.
That means: 1) season the chicken ahead and leave overnight to marinate; 2) season the Béchamel sauce well; and 3) season the vegetables during sauteeing.
Why not just season after everything has been assembled in the pan prior to baking / broiling? By that time, it will be too late. Fifteen minutes in the oven is not enough time for the chicken to absorb the seasoning. And what it manages to absorb will detract from the flavor of the sauce. So, season every step of the way.
Marinate the chicken
- Wipe the chicken thighs dry with a kitchen towel.
- Place the chicken thighs in a bowl, add the lemon pepper seasoning and toss thoroughly.
- Transfer the chicken to a covered container and marinate in the fridge for at least 12 hours. Twice as long is even better.
Brown the chicken
- Preheat the oven to 375F.
- Heat the cooking oil in a pan.
- Brown the chicken thighs in hot oil, in batches if your frying pan is not very large, flipping them over for even coloring (see notes after the recipe).
Assemble the chicken Bechamel
- In an oven-safe frying pan, melt the butter.
- Saute the onion until softened.
- Add the bell pepper and peas. Season with salt and pepper.
- Cook the vegetables for half a minute.
- Stir the Béchamel sauce into the vegetables.
- Arrange the browned chicken thighs on the Bechamel sauce.
Bake and broil the chicken Béchamel
- Bake at 375F for about 15 minutes or until the sauce is bubbly. The chicken should be cooked through at this point.
- Take the pan out of the oven.
- Turn up the heat to 400F and turn on the TOP heat.
- Place a mound of shredded cheese on top of each chicken.
- Put the chicken back in the oven and cook until the cheese is browned and lightly crisp.
- Optionally, sprinkle snipped greens (scallions or parsley) over the chicken Béchamel before serving.