- 2 tablespoons (1/4 stick) unsalted butter, divided
- 2 cups sugar
- 1 cup light corn syrup
- 1 cup water
- 1/4 teaspoon salt
- 2 cups blanched whole almonds, toasted , coarsely chopped
- 1/2 teaspoon baking soda
- 1 teaspoon flaked sea salt (such as Maldon)
- 5 large eggs, separated
- 1 cup sugar, divided
- 1/4 cup fresh tangerine juice or tangelo juice
- 2 tablespoons finely grated tangerine peel or tangelo peel
- 2 cups chilled heavy whipping cream
- 1 cup fresh tangerine juice or tangelo juice
- 2 tablespoons honey
- 2 tangerines, peeled, separated into segments
Coat large rimmed baking sheet with 1 tablespoon butter. Combine sugar, corn syrup, 1 cup water, and 1/4 teaspoon salt in heavy large saucepan. Stir over medium heat until sugar dissolves. Attach candy thermometer to side of pan. Increase heat to medium-high and bring to boil. Boil without stirring until mixture turns amber and thermometer registers 330°F to 340°F, about 10 minutes. Remove from heat; immediately stir in remaining 1 tablespoon butter, then almonds and baking soda (mixture will bubble). Working quickly, pour mixture out onto prepared baking sheet. Using offset metal spatula, quickly spread mixture into irregular 15×10-inch rectangle. Sprinkle 1 teaspoon sea salt evenly over brittle. Cool brittle completely at room temperature until firm, about 2 hours. DO AHEAD: Can be made 1 week ahead. Break brittle into irregular pieces and store in airtight container.
Coarsely chop enough brittle to measure 1 1/2 cups; store in airtight container while making semifreddo mixture.
Line 9x5x3-inch metal loaf pan with 2 layers of plastic wrap, leaving generous overhang on all sides. Fill large bowl with ice cubes and water. Whisk egg yolks, 1/2 cup sugar, tangerine juice, and tangerine peel in medium metal bowl. Set bowl with yolk mixture over saucepan of simmering water. Whisk constantly until mixture thickens and instant-read thermometer inserted into mixture registers 160&Deg;F, about 3 minutes. Remove bowl from over hot water and set over bowl with ice water. Using electric mixer, beat mixture until thick and cool, about 3 minutes. Remove bowl from over ice water.
Beat cream in another large bowl until peaks form; set aside. Using clean dry beaters, beat egg whites in another large bowl until soft peaks form. Gradually add 1/2 cup sugar, 1 tablespoon at a time, and beat until stiff but not dry. Fold 1/3 of egg whites into yolk mixture to lighten. Fold in remaining whites in 2 additions. Fold in whipped cream in 2 additions until just incorporated.
Spread 1/3 of semifreddo mixture (about 3 cups) evenly in loaf pan. Sprinkle 3/4 cup chopped brittle evenly over. Repeat layering with half of remaining semifreddo mixture; sprinkle remaining 3/4 cup brittle over, then spread remaining semifreddo mixture over (loaf pan will be very full and mixture will extend slightly over top of pan). Fold plastic wrap overhang over semifreddo to cover. Freeze overnight. DO AHEAD: Can be made 2 days ahead. Keep frozen.
Bring tangerine juice and honey to boil in heavy small saucepan over medium-high heat, stirring occasionally. Boil until mixture is syrupy and reduced to generous 1/3 cup, stirring often, about 10 minutes. Transfer to bowl; cool completely. Stir in tangerine segments. DO AHEAD: Can be made 8 hours ahead.Cover and chill.
Invert semifreddo onto platter. Remove plastic wrap. Dip large knife into hot water, wipe dry, then cut semifreddo crosswise into 1-inch-thick slices, dipping knife into water and wiping dry as needed. Place 1 slice on each plate. Spoon tangerine sauce alongside semifreddo and serve.