For the vanilla pudding:
- 1/2 cup granulated sugar
- 1/4 cup cornstarch
- 1/2 teaspoon salt
- 2 large eggs
- 1 large egg yolk
- 2 cups whole milk
- 1/2 cup heavy cream
- 2 teaspoons vanilla extract
For the vanilla simple syrup:
- 3/4 cup granulated sugar
- 1/2 cup water
- 1/2 vanilla bean, split and seeds scraped
For the whipped cream:
- 1/2 teaspoon unflavored powdered gelatin
- 2 tablespoons water
- 2 cups very cold heavy cream
- 1/4 cup granulated sugar
- 1 teaspoon vanilla extract
For building the trifle:
- 1 1/2 pounds strawberries, trimmed and quartered
- 1 1/2 pounds day-old pound cake, cubed
- Make the pudding: Place the sugar, cornstarch, and salt in a medium saucepan and whisk together, breaking up any clumps in the sugar or starch. Add the eggs and egg yolk and whisk until completely smooth. Whisk in the milk and cream. Heat over medium heat, stirring constantly with a wooden spoon or rubber spatula, until the mixture thickens and bubbles around the edge, 8 to 10 minutes. Remove the pan from the heat and whisk in the vanilla extract.
- Cool the pudding: Pour the finished pudding into a shallow pan. Place a layer of plastic wrap directly onto the custard, and chill for at least 2 hours before building the trifle.
- Make the syrup: Combine the sugar, water, and vanilla bean seeds in a small saucepan. Bring to a simmer over medium heat and cook until thickened slightly, about 5 minutes. Set aside to cool.
- Make the whipped cream: Mix the gelatin and water in a small bowl and set aside for 5 minutes to bloom. Microwave the gelatin until melted, 7 to 10 seconds. Place the cream, sugar, and vanilla in a stand mixer fitted with the whisk attachment. (Alternatively, use an electric hand mixer or hand whisk and large bowl.) Beat to soft peaks. With the mixer running or while whisking, pour in the gelatin and whip to stiff peaks.
- Build the trifle: Start with an even layer of pound cake in the bottom of a 2-quart trifle dish or clear glass bowl. Drizzle the cake with 1/2 cup of the vanilla syrup. Spoon 1/3 of the vanilla pudding onto the pound cake, gently pressing to force the pudding in between the pound cake pieces, then smoothing into an even layer. Top evenly with 1/3 of the strawberries, placing as many against the glass as possible for a beautiful presentation. Top with 1/3 of the whipped cream. Repeat with the layering twice more: pound cake, vanilla syrup, pudding, strawberries, and whipped cream.
- Garnish and refrigerate: Sprinkle the top of the trifle with any extra cake pieces or crumbs and strawberries. Refrigerate for at least 1 hour before serving.