How to Make It
To prepare custard, heat milk, 3 tablespoons sugar, and 1/8 teaspoon salt in a saucepan to 180° or until tiny bubbles form around edge (do not boil). Combine remaining 2 1/2 tablespoons sugar, cornstarch, egg, and egg yolks in a bowl, stirring with a whisk until smooth. Gradually add hot milk mixture to egg mixture, stirring constantly with a whisk. Return milk mixture to pan. Cook over medium heat until thick and bubbly (about 4 minutes), stirring constantly. Remove from heat; stir in vanilla. Place pan in an ice water-filled bowl 20 minutes or until mixture comes to room temperature; stir occasionally.
To prepare rhubarb, place 1/2 cup sugar, orange juice, 1/8 teaspoon salt, and rhubarb in a medium saucepan, and bring to a boil. Reduce heat, and simmer 15 minutes or until rhubarb breaks down and mixture thickens. Place the pan in an ice water-filled bowl until mixture cools to room temperature, stirring occasionally.
Arrange one-third of cake cubes in bottom of a 3-quart trifle dish. Arrange one-third of strawberries around edge and over top of cake. Spoon one-third of rhubarb over cake. Spoon one-third of custard over rhubarb. Repeat layers 2 more times. Carefully spread whipped topping over top. Sprinkle with nuts. Cover and refrigerate 4 hours or overnight.