Preheat oven to 400°F. Line a roasting pan and place the quartered peaches in it. Sprinkle with sugar. Roast for 10 minutes until soft and fragrant.

Remove from oven and set aside 1 peach worth of chunks for the sauce. Transfer the remaining peaches to a blender and puree until smooth. Let cool completely.

Make the Semifreddo Base

In a mixing bowl, whip eggs and sugar with an electric mixer or whisk until soft peaks form. Gently fold in the cooled peach puree, lemon juice, lemon zest, bourbon, and a pinch of kosher salt.

In a separate bowl, whip the heavy cream to soft peaks. Fold the whipped cream into the peach-egg mixture in thirds, gently folding to maintain airiness.

Line a freezer-safe container with plastic wrap. Transfer the semifreddo mixture to the container and smooth the top. Freeze for a minimum of 4 hours or until firm but scoopable.

Remove from freezer 5 minutes before serving. Slice and spoon the reserved chopped peaches as a sauce over each portion. Enjoy immediately.