Instructions

1. Place 2 sticks unsalted butter in the bowl of a stand mixer (or large bowl if using an electric hand mixer). Place 4 large eggs and 1/2 cup whole milk on the counter. Let sit at room temperature until the butter is softened.
2. Arrange a rack in the middle of the oven and heat the oven to 375°F. Remove 1 tablespoon butter from the bowl and use it to coat 2 (9x5-inch) loaf pans. If desired, line each pan with a parchment paper sling that hangs off the two long sides.
3. Pour 1 can sliced peaches and their juices into a blender and blend until completely smooth, about 1 minute.
4. Finely grate the zest of 2 medium lemons into a large bowl (about 2 tablespoons). Add 4 cups all-purpose flour, 1 teaspoon baking powder, and 1/2 teaspoon kosher salt, and whisk to combine.
5. Add 2 cups granulated sugar to the bowl of butter. Beat with the paddle attachment on low speed until combined, about 30 seconds. Increase the speed to medium high and beat until lightened in color and fluffy, 1 to 2 minutes, scraping down the sides of the bowl as needed.
6. Beat in the eggs one at a time on medium speed, waiting until each egg is incorporated before adding the next. Pour in the blended peaches and milk and beat on medium speed until combined, about 30 seconds.
7. Add the flour mixture in 3 increments and beat on low speed until thoroughly combined. Pour the batter into the loaf pans.
8. Bake until a tester inserted in the center of a loaf comes out clean, 1 hour to 1 hour and 15 minutes. (This is a good time to make the custard.) Place the pans on a wire rack and let cool 20 minutes. Remove the cakes from the pans and let cool completely on a wire rack. Meanwhile, make the caramel and macerated peaches.
9. Place 2 cups peach preserves in a small saucepan, sprinkle with 1 packet gelatin, and stir to combine. Let sit 5 minutes for the gelatin to hydrate. Meanwhile, cut 4 tablespoons unsalted butter into 1/2-inch pieces. Finely grate the zest of 1 medium lemon.
10. Heat the peach mixture on low, stirring occasionally, until the mixture is warm to the touch and the gelatin is dissolved. Remove from the heat.
11. Bring 3 cups whole milk and 1/4 cup heavy cream to a boil in a large saucepan over medium heat. Meanwhile, place 1/4 cup granulated sugar, 1/4 cup sweet iced tea mix, and 1/4 cup cornstarch in a large bowl and whisk to combine. Add 4 large egg yolks and 1 large egg and whisk to combine.
12. While whisking constantly, slowly pour the milk mixture into the egg mixture and whisk until combined. Pour everything back into the saucepan. Cook over low heat, whisking constantly and stirring with a heatproof spatula to get into the corners of the pan, until the mixture bubbles.
13. Remove from the heat. Add the butter and 1/2 teaspoon kosher salt and or blend directly in the saucepan with an immersion blender until smooth. (Alternatively, blend in a stand blender.) Transfer to a large bowl, add the peach preserves and lemon zest, and stir to combine.
14. Press a sheet of plastic wrap directly onto the surface of the custard to prevent a skin from forming. Let cool at room temperature 15 minutes, then refrigerate until chilled, at least 4 hours or overnight.
15. Cut 6 tablespoons unsalted butter into 6 pieces and let sit at room temperature until softened. Place 1/2 cup heavy cream and 2 tablespoons sweet iced tea mix in a small bowl and stir to combine.
16. Place 1 cup granulated sugar in a medium saucepan over medium heat and stir continuously until melted, about 5 minutes.
17. Remove from the heat. Add the butter and stir until melted — be careful, the caramel will begin to bubble violently! Add the cream mixture and stir until combined and smooth. Let cool for 15 to 20 minutes.
18. Finely grate the zest from 1 medium lemon and set aside for the whipped cream.
19. Juice the lemon into a large bowl. Halve, pit, and cut 4 large peaches into 1/2-inch pieces. Add the peaches to the bowl, sprinkle with 2 tablespoons granulated sugar, and toss to combine. Let sit at least 1 hour or refrigerate up to 1 day.
20. Place the reserved lemon zest, 1 cup cold heavy cream, and 2 tablespoons powdered sugar in a large bowl and whisk until soft peaks form.
21. Cut the pound cake into 1/4-inch cubes. Set aside 1/4 cup of the caramel (heat in the microwave if needed until warm and pourable) for drizzling on the top of the trifles.
22. Assemble the trifles in 8 (pint-sized) Mason jars: divide 1/3 of the custard into the jars, top with 1/3 of the cake, drizzle with 1/3 of the remaining caramel, and top with 1/3 of the macerated peaches. Repeat this layering twice more to use up the custard, cake, caramel, and peaches.
23. Top with the whipped cream and drizzle with the reserved caramel.