Ingredients:
- 3 lbs medium zucchini, trimmed and thinly sliced (about 1/8 inch)
- 1 tsp salt
- 4 tbsp unsalted butter
- 4 oz full-fat cream cheese, softened
- 1 cup heavy cream
- 1/2 cup low sodium chicken or vegetable broth
- 3 cloves garlic, minced finely
- 1/2 tsp xanthan gum
- 1/2 tsp ground black pepper
- 1/2 tsp dried thyme
- Pinch of nutmeg
- 1 tsp Dijon mustard
- 1 cup freshly grated Gruyère cheese
- 1/2 cup freshly grated Parmesan cheese (Parmigiano-Reggiano)
- 2 tbsp fresh parsley, chopped (for garnish)
Instructions:
- Preheat oven to 375°F (190°C). Lightly grease a 9x13 inch baking dish. Place sliced zucchini in a colander, toss with 1 tsp salt, and let sit for 15 minutes to draw out excess water. Pat thoroughly dry with paper towels.
- In a large skillet over medium heat, melt the butter. Add minced garlic and sauté for 1 minute until fragrant.
- Whisk in the cream cheese until it melts smoothly into the butter. Slowly pour in the heavy cream and broth, whisking continuously until smooth. Bring the mixture to a gentle simmer.
- In a small bowl, whisk the xanthan gum with a tablespoon of cold water to create a slurry. Whisk the slurry into the simmering sauce. Add thyme, nutmeg, Dijon, pepper, and half of the Gruyère. Whisk until the sauce thickens to coat the back of a spoon (about 2–3 minutes). Remove from heat.
- Stir half of the Parmesan into the sauce. Taste and adjust seasoning. Layer about one-third of the dried zucchini slices into the prepared baking dish. Pour one-third of the sauce evenly over the top. Repeat layers until all zucchini and sauce are used, finishing with sauce on top.
- Sprinkle the remaining Gruyère and Parmesan cheese evenly over the top layer.
- Bake uncovered for 40–45 minutes, or until the top is deeply golden brown and the sauce is bubbling thickly around the edges. Loosely tent with foil if the top browns too quickly.
- Let the gratin rest on the counter for 10 minutes before slicing. Garnish generously with fresh parsley before serving.