Preheat the oven to 375°F (190°C).

Wash and slice the zucchinis into thin rounds.

In a mixing bowl, whisk together the heavy cream, minced garlic, salt, pepper, and nutmeg.

In your baking dish, arrange half of the zucchini slices in an even layer.

Sprinkle half of the Gruyere and Parmesan cheeses over the zucchini.

Pour half of the cream mixture over the layered zucchinis and cheese.

Repeat the layering process with the remaining zucchini, cheeses, and cream mixture.

In a small bowl, mix the breadcrumbs with melted butter and sprinkle them over the top.

Bake for 30 minutes until the top is bubbly and golden brown.

For an extra crispy topping, broil for the last 2-3 minutes, watching closely.