Lemon-Olive Oil Semifreddo with Blueberry Compote

Place 1 tablespoon lemon juice in a small bowl, and sprinkle with gelatin; let stand until gelatin softens, about 5 minutes.

Fill a large saucepan with water to a depth of a few inches. Bring to a simmer over medium. Stir together sugar, salt, and lemon zest in a metal bowl that will fit into the pan of simmering water. Work sugar and zest between your fingers until sugar is moist and aromatic. Whisk in eggs, then remaining 11 tablespoons lemon juice. Set bowl over pan of simmering water (do not allow bowl to touch water). Cook, whisking constantly, until mixture is thick and a candy thermometer registers 180°F, about 12 minutes; remove from heat. Whisk in softened gelatin-lemon mixture, and stir until dissolved. Pour through a fine mesh strainer into a blender; discard solids. Let mixture rest in blender at room temperature, pulsing occasionally, until it cools to 130°F, about 15 minutes.  

With blender running, add butter in 2 additions, processing until incorporated after each addition. With blender running, slowly and steadily drizzle in olive oil; process until combined, about 1 minute. Pour Lemon Cream into a medium bowl; press plastic wrap against surface. Refrigerate until firm, at least 6 hours and preferably overnight (12 hours).

Line bottom and long sides of a 9-inch loaf pan with parchment paper, leaving a 2-inch overhang on long sides. Place whipping cream in a medium bowl. Using a whisk or an electric mixer, beat until soft peaks form , about 2 minutes. Cover and refrigerate until ready to use.

Transfer Lemon Cream to a large bowl, and whisk vigorously to loosen; set aside. Place egg whites and salt in bowl of a stand mixer fitted with a whisk attachment; set aside.

Stir together sugar, water, and corn syrup in a small saucepan until combined. Cook over medium-high, undisturbed, and when syrup registers 230°F on a candy thermometer, begin whipping egg whites with stand mixer. Beat whites until soft peaks form and syrup in pan registers 240°F, about 3 minutes. With mixer running on high speed, slowly stream hot sugar syrup down side of bowl, being careful not to touch whisk. Beat until bowl no longer feels warm to touch and meringue is stiff and shiny, about 5 minutes.  

Whisk one-third of the meringue into Lemon Cream. Fold in remaining meringue in 2 additions. Add chilled whipped cream, and fold gently just until combined. Pour into prepared loaf pan. Cover and freeze Semifreddo overnight (12 hours).

Stir together sugar and 1 cup of the blueberries in a medium saucepan. Bruise blueberries using back of a spoon to release some juices. Cook over low, stirring often, until blueberries have popped and broken down, 5 to 8 minutes. Pour through a fine mesh strainer into a medium bowl, pressing on solids in strainer; discard solids. Add remaining 1 1/2 cups blueberries to cooked blueberry juices in bowl, and toss to combine.

Dip an offset spatula or a thin knife into hot water; wipe dry with a kitchen towel, and run along the short sides of the loaf pan. Grasp the parchment paper overhang, and lift Semifreddo from loaf pan. Carefully peel parchment off Semifreddo, and discard. Place Semifreddo on a platter. Cover with Blueberry Compote. Slice and serve.