Ingredients

• 3.3 pounds potatoes, peeled and cut into chunks
• 2 tablespoons butter, for the mash
• 5 tablespoons heavy cream
• 2 egg yolks
• 2 tablespoons butter, for the filling
• 7 shallots, chopped
• 3 carrots, chopped
• 2 celery stalks, chopped
• 1 garlic clove, finely chopped
• 4 tablespoons white wine
• 1 tablespoon tomato paste
• 1 can (14 ounces) canned diced tomatoes
• 1 1/2 cups chicken stock
• 1 1/3 pounds cooked chicken, shredded
• 16 black olives
• 2 tablespoons chopped fresh parsley
• 2 ounces Gruyere cheese, grated

Equipment

• Large pot
• Potato ricer or masher
• Large skillet
• 8 by 12 inch baking dish
• Box grater

Instructions

1. Boil the potatoes in a large pot of salted water until a knife slides through easily, about 15 to 20 minutes, then drain well so the mash doesn't turn watery.
2. Push the potatoes through a ricer or mash them thoroughly until smooth, then stir in the butter, heavy cream, and egg yolks. Season with salt and pepper and set aside; the yolks help the top set and brown later.
3. Melt the butter in a large skillet over medium heat. Add the shallots, carrots, and celery and cook gently until softened, about 8 minutes, so they sweeten and lose their raw bite, then stir in the garlic and cook 1 minute until fragrant.
4. Pour in the white wine and let it bubble for 1 minute to cook off the sharp alcohol, then stir in the tomato paste, canned tomatoes, and chicken stock.
5. Simmer for 10 to 15 minutes, until the sauce thickens enough to coat a spoon and no longer looks watery.
6. Stir in the shredded chicken, olives, and parsley, then taste and adjust the salt and pepper.
7. Preheat the oven to 350F. Spread the filling into an 8 by 12 inch baking dish and spoon the mashed potato evenly over the top, spreading it to the edges to seal in the sauce.
8. Scatter the grated Gruyere over the potatoes and bake for 30 to 35 minutes, until the filling is bubbling at the edges and the top is golden brown.