Adjust oven rack to upper-middle position and heat oven to 325°Place 2 unpeeled bananas on baking sheet and bake until skins are completely black, about 20 minutes. Let cool 5 minutes.

Meanwhile, whisk 1⁄4 cup sugar, egg yolks, and cornstarch in medium bowl until smooth. Bring half-and-half, remaining sugar, and salt to simmer over medium heat in large saucepan. Whisk 1⁄4 cup simmering half- and-half mixture into egg yolk mixture. Slowly whisk tempered yolk mixture into saucepan. Cook, whisking constantly, until mixture is thick and large bubbles appear at surface, about 2 minutes. Remove from heat and stir in butter and vanilla.

Transfer pudding to food processor. Add warm peeled roasted bananas and 1 tablespoons lemon juice and process until smooth. Scrape into large bowl and place plastic wrap directly on surface of pudding. Refrigerate until slightly cool, about 45 minutes.

Cut remaining bananas into 1⁄4-inch slices and toss in bowl with remaining lemon juice. Spoon one-quarter of pudding into 3-quart trifle dish and top with layer of cookies, layer of sliced bananas, and another layer of cookies. Repeat twice, ending with pudding. Place plastic wrap directly on surface of pudding and refrigerate until wafers have softened, at least 8 hours or up to 2 days.

Note: I assembled the pudding in 8 ounce canning jars, finishing the top layer with crushed wafers.

With electric mixer on medium speed, beat cream, sugar, and vanilla until stiff peaks form, about 2 minutes. (Whipped cream can be refrigerated for 4 hours.) Top banana pudding with whipped cream. Serve.