Prep time: 15 minutes
Total time: 5 hours
for the candied oranges:
8 orange slices (1/4-inch thick)
1 cup|192 grams granulated sugar
1/3 cup|70 ml sparkling white wine
1 tablespoon Aperol
1 teaspoon lemon juice
for the crust:
1 1/4 cups|150 grams vanilla wafer crumbs (from around 45 cookies)
1/2 teaspoon kosher salt
7 tablespoons unsalted butter, melted and cooled
for the filling:
1/4 cup|60 ml Aperol
2 teaspoons unflavored powdered gelatin
3/4 cup|190 grams granulated sugar
3/4 cup|187 ml sparkling white wine
1/2 teaspoon kosher salt
finely grated zest of 1 orange
2 large egg whites
1. Make the candied oranges: Using a Microplane zester, grate the zest from the orange into a small bowl; cover the bowl with plastic wrap and reserve the zest. Trim the ends off the orange and cut into at least 8 slices. Halve the slices to produce 16 half-moons. Place the orange slices in a wide, heatproof bowl, cover with 3 cups water, then microwave until the water starts boiling, 8 to 10 minutes. Drain off the water, leaving the orange slices in the bowl.
2. Add the sugar to the orange slices, toss to coat, then pour in the wine, Aperol, and lemon juice and toss gently until the sugar is evenly moistened. Microwave the oranges again until the sugar dissolves and the oranges are tender, 6 to 8 minutes. Remove the bowl from the microwave and let the oranges cool in the syrup to room temperature.
3. Using a fork, transfer the orange slices to a plastic storage container then pour the syrup over them to cover. Refrigerate the slices until chilled, at least 4 hours or up to 1 month.
4. Make the crust: In a bowl, whisk together the cookie crumbs and salt. Add the butter and toss with a fork until evenly moistened. Transfer the crumbs to a 9-inch pie pan, and press it evenly into the bottom and up the side to make a uniform crust.
5. Make the filling: Pour the Aperol in a small bowl, and sprinkle with the gelatin. Let stand for 5 minutes to allow the gelatin to hydrate. Place the bowl in the microwave and heat just until the Aperol is warm, about 30 seconds. Stir to dissolve the gelatin then pour the mixture into a medium bowl. Pour in 1/2 cup sugar, the wine, salt, and orange zest, and stir until the sugar dissolves.
6. In a large bowl, beat the egg whites on medium speed of a hand mixer until they start to form soft peaks. Slowly pour in the remaining 1/4 cup sugar and beat until the meringue forms stiff peaks. Pour in the gelatin mixture and whisk gently until smooth. (The filling will be pourable, not fluffy like mousse.)
7. Finely dice 8 of the orange half-moons and sprinkle over the bottom of the pie crust. Slowly pour the filling into the pie crust and refrigerate until set, at least 4 hours or up to 1 day in advance.
8. To serve, dot the top of the filing with the remaining 4 orange half-moons, cut into small triangles. Cut the pie into 8 wedges and serve cold.