Silver Palate's St. Germain Tart – Table Terrain

Ingredients

• 4 tablespoons (½ stick) unsalted butter
• 6 leeks, trimmed, well washed, and thinly sliced
• 2 eggs
• 2 egg yolks
• 1 cup half-and-half
• 1 cup heavy cream
• Salt and freshly ground black pepper, to taste
• One 9-inch shell of Pâte Brisée, partially baked
• ½ cup grated Gruyère cheese