Yield: approximately 1½ dozen
1. Preheat oven to 350°. Line a 13x9-inch baking pan with aluminum foil, letting it hang over sides by at least 2 inches.
1 cup unsalted butter, softened
¾ cup confectioners’ sugar
½ teaspoon vanilla extract
2 cups all-purpose flour
¼ cup finely ground hazelnuts
1 tablespoon ground ginger
¼ teaspoon salt
1 egg yolk
1 (8-ounce) package cream cheese, softened
1 (8-ounce) container mascarpone cheese, softened
2 (14-ounce) cans sweetened condensed milk
4 large eggs
1 tablespoon lemon zest
1 cup fresh lemon juice
6 tablespoons boiling water
1 tablespoon unflavored gelatin
Garnish: lemon slices and fresh lavender
2. In a medium bowl, beat butter, confectioners’ sugar, and vanilla at medium-high speed with an electric mixer until creamy, approximately 3 minutes. Reduce mixer speed to low, and add flour, hazelnuts, ginger, and salt. Add egg yolk, beating to combine. Press mixture into the bottom of prepared pan.
3. Bake until light golden brown, approximately 10 minutes. Remove from oven, and let cool completely on a wire rack.
4. Meanwhile, in a large bowl, beat cream cheese at high speed with an electric mixer until creamy, approximately 3 minutes. Add mascarpone, and beat until combined. Add condensed milk, beating until smooth. Add eggs, one at a time, beating well after each addition. Add lemon zest and lemon juice, and beat until mixture is thick and smooth.
5. In a small bowl, combine 6 tablespoons boiling water and gelatin, whisking until gelatin is dissolved; let cool for approximately 5 minutes. Add gelatin mixture to lemon mixture, beating until combined. Spread lemon mixture onto prepared crust. Refrigerate for at least 8 hours or overnight.
6. Using foil overhang, lift bars from pan. Cut into 2½- to 3-inch squares. Store, covered, in refrigerator for up to 3 days.
7. Garnish with lemon slices and lavender, if desired.