How to Make It
Preheat oven to 350°. Melt 6 tablespoons butter in a small saucepan over medium-low heat; cook 6 minutes or until golden brown, stirring frequently. Let cool 5 minutes.
Place wafer crumbs, brown sugar, and 1/8 teaspoon salt in the bowl of a food processor; pulse to combine. Drizzle melted butter over top of crumb mixture; pulse to combine. Press crumb mixture into the bottom and up the sides of a 9-inch round removable-bottom tart pan coated with cooking spray. Bake 12 to 14 minutes or until crust is lightly browned. Let cool completely on a wire rack.
Combine cranberries and 3 tablespoons water in the bowl of a food processor; process until smooth. Combine cranberry puree, 1/4 cup granulated sugar, 2 tablespoons butter, and 1/8 teaspoon salt in a small saucepan over medium-high heat; bring to a boil. Whisk together 1 teaspoon cornstarch and 1 egg in a medium bowl. Drizzle hot cranberry mixture into egg mixture, whisking constantly until combined. Return mixture to pan over medium heat; cook, stirring constantly, about 3 minutes or until mixture thickens. Pour mixture through a fine wire-mesh strainer into a bowl, pressing on solids with the back of a spoon; discard solids.
Combine orange zest and juice, remaining 1/2 cup granulated sugar, remaining 8 tablespoons butter, and remaining 1/8 teaspoon salt in a medium saucepan over medium-high heat; bring to a boil. Whisk together egg yolks, remaining 1 tablespoon cornstarch, and remaining 4 eggs in a medium bowl. Gradually drizzle hot orange mixture into egg mixture, whisking constantly. Return mixture to pan over medium heat; cook 4 to 5 minutes or until mixture thickens, stirring constantly. Pour mixture through a fine wire-mesh sieve into a bowl, pressing on solids with the back of a spoon; discard solids. Spread orange filling into cooled crust, smoothing top. Spoon cranberry mixture over filling; smoothing top. Let tart cool to room temperature on a wire rack. Cover and refrigerate 8 hours.