Make Chicken Cordon Bleu tonight: tender chicken rolled with ham and Swiss, baked and finished with a creamy mustard-Parmesan sauce.
Preheat the oven to 350°F and prepare your rectangular rimmed baking sheet or baking dish by spraying it lightly with cooking spray or lining it with a sheet of parchment paper. This simple step sets the stage so everything you assemble later goes straight onto a clean, low-profile rectangle that will carry through to the final presentation.
Place each boneless, skinless chicken breast between two pieces of plastic wrap and, with the flat side of a meat tenderizer, gently pound each to about 1/4-inch thickness. Season both sides with kosher salt and freshly ground black pepper; the thin, even chicken will cook through quickly and give you a delicate, tender texture once rolled.
Top each flattened breast with a single slice of deli ham and roughly 1 ounce of Swiss (or Gruyere) cheese, centered. Roll each breast jelly-roll style so the ham and cheese are neatly enclosed, tucking the ends under as you go to form compact cylinders. Secure each roll with a toothpick so they hold their shape while being handled.
Combine the melted butter with the minced garlic in a small shallow bowl so it’s ready for brushing. In a separate bowl mix the seasoned breadcrumbs with dried thyme until the mixture is evenly speckled. These two simple bowls — glossy garlic-butter and coarse thyme-scented crumbs — create the contrast that becomes the crisp, aromatic crust.
Brush each rolled chicken with the garlic-butter, then press and roll it in the breadcrumb-thyme mixture until well coated. Arrange the breaded rolls in the prepared rectangular baking dish in a single layer with a little space between them so the crust browns evenly. This is the visual milestone where raw transforms into something pre-bake and textured — the golden breadcrumbs glint with butter and the toothpicks peek out from tidy spirals.

Place the baking dish in the preheated oven and bake for 35–40 minutes, or until an instant-read thermometer inserted into the center registers 165°F and the crust is deep golden-brown and crisp. Remove from the oven and carefully lift out the rolls; remove the toothpicks so the finished slices will look seamless and inviting.
In a small saucepan, melt butter over medium heat and stir in the flour to form a light roux, cooking for a minute. Gradually whisk in the milk and white wine a little at a time until smooth, then whisk in Dijon mustard, dissolved chicken bouillon, and Worcestershire sauce. Bring to a gentle boil while whisking, reduce heat and simmer for a minute, then remove from heat and stir in shredded Parmesan until silky. Taste and adjust with salt and pepper.
Transfer the baked rolls to a rectangular serving platter that echoes the baking dish's geometry. Slice one or two rolls crosswise to reveal the ham-and-melted-cheese spiral inside, spoon the warm creamy sauce over and around the slices so it cascades and pools slightly, and finish with a light scattering of chopped parsley and a few grinds of black pepper for contrast. Serve immediately while the cheese is molten and the crust is crisp.
