Chocolate Caramel Walnut Tart | America's Test Kitchen

Ingredients

• 1 large egg , separated
• 1/4 teaspoon vanilla extract
• 1/2 cup toasted walnuts (2 1/2 ounces/71 grams), see note
• 1/2 cup confectioners' sugar (2 ounces/57 grams)
• 1 cup unbleached all-purpose flour (5 ounces/142 grams)
• 1/8 teaspoon table salt
• 5 tablespoons unsalted butter (cold), cut into 1/2-inch cubes
• 1/4 cup water
• 1 cup granulated sugar (7 ounces/198 grams)
• 2/3 cup heavy cream
• 3 tablespoons unsalted butter , cut into 3 pieces
• 1/2 teaspoon vanilla extract
• 1/2 teaspoon lemon juice from 1 lemon
• 16-18 walnut halves , plus 1 cup (5 ounces) toasted walnuts, coarsely chopped (see note)
• 2 large egg yolks
• 1 tablespoon heavy cream
• 1/3 cup heavy cream
• 1/3 cup whole milk
• 5 ounces (142 grams) semisweet chocolate , chopped fine
• 2 tablespoons unsalted butter , cut into 4 pieces