Potato Gratin with Tomatoes, Gruyère, and Thyme

"I found this recipe on Pinterest.  The recipe came from HERE and she adapted it from The Foster's Market Cookbook, by Sara Foster.  This was so delish and smelled wonderful while cooking.  I regret not letting it "rest 10-15 minutes before serving" because it was very soupy and did not come out in pretty slices like in her photo.  I also had some curdling going on, which I wonder could be avoided by warming the half and half first.   I don't think I used enough salt and I would add garlic, onion powder (or thinly sliced onions) and maybe even crumbled bacon.  I definitely want to try other variations."

INGREDIENTS:
8 Tablespoons (4 ounces) unsalted butter, melted and divided
3 pounds Yukon Gold potatoes, peeled
Kosher salt and freshly ground black pepper to taste
3 Tablespoons fresh thyme, chopped (I used dried because it was what I had on hand)
2 cups (8 ounces) grated Gruyère cheese (I used Swiss as a cheaper substitute)
1 cup (4 ounces) grated Parmesan cheese
1 large tomato (10 ounces) cored and thinly sliced into 1/4-inch thick rounds
1 cup half-and-half
1 cup chicken broth
1/2 cup fresh bread crumbs
1/2 cup panko crumbs

DIRECTIONS:

Preheat the oven to 350º F.  Brush the bottom and sides of a 9 x 13-inch baking dish with 2 Tablespoons of the melted butter.

Slice two of the potatoes as thinly as possible, about 1/8-inch thick.  Arrange a single layer of the potatoes on the bottom of the baking dish.  Top with a second layer of potatoes.  (It is best to slice the potatoes as needed per layer because the starch in the potatoes helps hold the layers together).  Brush the potatoes lightly with a portion of the melted butter.  Sprinkle with salt and pepper, about 2 teaspoons of the thyme, 2 tablespoons of the Gruyère, and 1/3 cup of the Parmesan.

Slice and add 2 more layers of potatoes, brush lightly with melted butter.  Sprinkle with salt and pepper, about 2 teaspoons of the thyme, about 2 tablespoons of the Gruyère, and 1/3 cup Parmesan.  Add a single layer of tomatoes and top with 2 tablespoons of the Gruyère, 1/3 cup of the Parmesan, 2 teaspoons of the thyme, and season lightly with salt and pepper.

Continue this process with two more layers of potatoes.  Press firmly with the palm of your hand to pack all of the ingredients together.  Brush lightly with the melted butter, sprinkle with the remaining thyme, season lightly with salt and pepper, and sprinkle with the remaining Gruyère.

In a small bowl, combine the bread crumbs and panko; set aside.  Pour the half-and-half and the chicken broth over the potatoes and top with the bread crumb mixture.  Drizzle the remaining butter over the bread crumb mixture and bake, covered with foil, for 45-50 minutes.  Remove the foil and bake uncovered for 30-40 minutes longer or until the gratin is bubbling and golden on top and the potatoes are soft when pierced with the tip of a sharp paring knife.  Let rest 10-15 minutes before serving.  Serve warm.  Enjoy!