Can I make this ahead?
Yes. Assemble the chicken, ham, and cheese on a baking sheet, cover, and refrigerate up to 4 hours. Pour the Dijon cheese sauce over just before baking.
What can I use instead of Swiss cheese?
Gruyère, provolone, or fontina work well. Avoid processed cheese slices, which may not melt evenly under the sauce.
How do I know when the chicken is done?
Internal temperature should reach 165°F (74°C) at the thickest part. Check with an instant-read thermometer to avoid overcooking.
Can I use chicken thighs instead of breasts?
Yes, but increase baking time by 5–8 minutes since thighs are thicker. Check for 165°F internal temperature.
How do I store leftovers?
Cover and refrigerate up to 3 days. Reheat in a 350°F oven for 10–12 minutes until warmed through.