👨‍🍳 Instructions

1. 1

   Preheat your oven to 200°C (400°F). Grease a medium-sized gratin dish with butter.

   💡 Tip: Ensuring the dish is well-greased prevents sticking.
2. 2

   In a bowl, whisk together the heavy cream, milk, chopped dill, salt, and pepper.

   💡 Tip: A good whisking incorporates air, making the sauce lighter.
3. 3

   Arrange a layer of thinly sliced potatoes in the bottom of the prepared gratin dish. Scatter half of the chopped herring over the potatoes.

   💡 Tip: Uniformly sliced potatoes ensure even cooking.
4. 4

   Pour about a third of the cream mixture over the potato and herring layer. Repeat with another layer of potatoes, the remaining herring, and another third of the cream mixture.

   💡 Tip: Distributing the herring evenly ensures each serving has fish.
5. 5

   Top with the final layer of potatoes and pour the remaining cream mixture over the top. If using, sprinkle the grated Gruyere cheese over the gratin.

   💡 Tip: The cheese topping adds a golden, crispy crust.
6. 6

   Cover the gratin dish with foil and bake for 30 minutes. Remove the foil and bake for another 20-25 minutes, or until the potatoes are tender and the top is golden brown and bubbly.

   💡 Tip: Covering initially steams the potatoes, while uncovering allows browning.
7. 7

   Let the gratin rest for 5-10 minutes before serving. Garnish with extra fresh dill if desired.

   💡 Tip: Resting allows the gratin to set, making it easier to serve.