Step 1Preheat oven to 400 degrees F. Whisk together sugar and flour in a medium-size heavy saucepan. Gradually whisk in milk until blended. Cook over medium heat, whisking constantly, 5 minutes or until thickened.Step 2Whisk egg yolks until thick and pale. Gradually whisk about one-fourth of hot milk mixture into yolks; add yolk mixture to remaining hot milk mixture, whisking constantly. Pour into a clean saucepan. Cook over low heat, whisking constantly, 5 minutes or until thickened. Remove from heat; stir in 2 tablespoons vanilla.Step 3Toss together vanilla wafers and banana slices in an 11 x 7-inch baking dish. Top with warm pudding.Step 4Beat egg whites at high speed with an electric mixer until foamy. Gradually add 1/4 cup sugar, 1 tablespoon at a time, beating until stiff peaks form and sugar dissolves (about 2 to 4 minutes). Beat in 1/8 teaspoon vanilla with the last tablespoon of sugar. Spread meringue over warm pudding, sealing to edges of dish. Bake at 400 degrees F. for 8 minutes or until golden brown. Let stand 30 minutes. Serve warm.