potato dish for Easter — Les Petites Gourmettes

Ingredients

• 1 ounce dried porcini mushrooms
• 1/2 cup mushroom soaking liquid
• 2 tablespoons unsalted butter, softened, plus more for the dish
• 1 cup heavy cream
• 2 garlic cloves, peeled and minced
• 1 ½ pounds Yukon Gold potatoes
• 2 leeks (white and pale-green parts only), thinly sliced and rinsed well
• Coarse salt