Spring Bouquet Cake with Fruit Filling

Name: Spring Bouquet Cake with Fruit Filling
Ingredients: 12 oz. fresh rhubarb, trimmed, stalks cut in 1⁄2-inch pieces (2 cups) or 2 cups frozen cut rhubarb; 1 c. fresh strawberries, hulled and halved, or 1 cup unsweetened frozen strawberries; ½ c. granulated sugar; 1 tbsp. cornstarch; .13 tsp. salt; 1¾ c. cake flour (not self-rising); 2 tsp. baking powder; ¼ tsp. salt; ½ c. milk; 1 stick unsalted butter or margarine (not spread); 1 tbsp. finely grated lemon peel; 1 tbsp. fresh lemon juice; 2 tsp. vanilla extract; Yolks from 4 large eggs (save whites for omelets or another use), at room temperature; 2 large eggs; 1¼ c. granulated sugar; 1 pt. heavy (whipping) cream; ½ c. confectioners’sugar; 1 tsp. vanilla extract; Decoration: sugared edible flowers or strawberry fans (see note)