Follow the steps in order for the best result.
Begin by preheating your oven to 425°F (220°C). Prepare a 9x9 inch glass baking dish with a non-stick cooking spray to prevent sticking.
In a frying pan over medium heat, melt the butter. Add the sliced mushrooms and sauté for approximately 5 minutes, until they soften and release their moisture.
While the mushrooms are cooking, in a large mixing bowl, combine the mashed potatoes, beaten eggs, salt, pepper, and cardamom powder. Mix thoroughly to ensure all ingredients are well incorporated.
Evenly spread the sautéed mushrooms across the bottom of the prepared glass baking dish. Then, carefully spread the potato mixture over the mushrooms, ensuring an even layer.
Place the baking dish in the preheated oven and bake for 15-20 minutes, or until the top of the potato bake is lightly browned and heated through.
Remove from the oven and sprinkle the chopped chives over the top. Serve immediately and enjoy this comforting Norwegian-inspired dish.