Preparation Preheat oven to 350°F. Roll out puff pastry on lightly floured surface to 12-inch square. Line 9-inch-diameter tart pan with removable bottom with pastry, cutting off excess at edge. Using fork, pierce dough all over. Freeze pastry 5 minutes. Cover pastry with aluminum foil. Fill with dried beans or pie weights. Bake pastry 15 minutes. Remove weights and foil. Bake crust until golden, about 5 minutes longer. Cool completely on rack. (Can be prepared 1 day ahead. Cover with plastic wrap. Let stand at room temperature.) Preheat oven to 425°F. Heat olive oil in heavy large skillet over medium heat. Add sliced leeks and sauté until soft, about 5 minutes. Add whipping cream and simmer until leek mixture is reduced to 1 1/4 cups, about 5 minutes. Let mixture cool. Using wooden spoon, beat herb cheese, goat cheese, and cream cheese in large bowl until well blended. Stir in leek mixture, then lemon juice and thyme. Season mixture to taste with salt and pepper. Stir in eggs 1 at a time, blending well after each addition. Spread half of filling over bottom of crust. Top with smoked salmon. Top salmon with remaining filling. Sprinkle with breadcrumbs. Bake tart until filling is set, about 30 minutes. Transfer to platter. Let tart cool to room temperature. Cut tart into wedges and serve.
Preparation Preheat oven to 350°F. Roll out puff pastry on lightly floured surface to 12-inch square. Line 9-inch-diameter tart pan with removable bottom with pastry, cutting off excess at edge. Using fork, pierce dough all over. Freeze pastry 5 minutes. Cover pastry with aluminum foil. Fill with dried beans or pie weights. Bake pastry 15 minutes. Remove weights and foil. Bake crust until golden, about 5 minutes longer. Cool completely on rack. (Can be prepared 1 day ahead. Cover with plastic wrap. Let stand at room temperature.) Preheat oven to 425°F. Heat olive oil in heavy large skillet over medium heat. Add sliced leeks and sauté until soft, about 5 minutes. Add whipping cream and simmer until leek mixture is reduced to 1 1/4 cups, about 5 minutes. Let mixture cool. Using wooden spoon, beat herb cheese, goat cheese, and cream cheese in large bowl until well blended. Stir in leek mixture, then lemon juice and thyme. Season mixture to taste with salt and pepper. Stir in eggs 1 at a time, blending well after each addition. Spread half of filling over bottom of crust. Top with smoked salmon. Top salmon with remaining filling. Sprinkle with breadcrumbs. Bake tart until filling is set, about 30 minutes. Transfer to platter. Let tart cool to room temperature. Cut tart into wedges and serve.