1 cup plus 1 teaspoon whole milk, divided
3 egg yolks
1/2 cup sugar, divided
2 tablespoons cornstarch, divided
1 tablespoon all-purpose flour
4 tablespoons unsalted butter, softened
1 tablespoon orange zest
2 large eggs, divided
1 tablespoon orange liqueur*
1/4 teaspoon salt
1/4 cup almond flour
1 (17.3-ounce) package frozen puff pastry, thawed (2 sheets)
1 almond or piece of candied fruit
1/4 cup maple syrup
In a large saucepan, bring 1 cup milk to a boil over medium-high heat, whisking constantly. Remove from heat. In a medium bowl, whisk together egg yolks, 1/4 cup sugar, 1 tablespoon cornstarch, and flour.
Add about 1/2 cup hot milk mixture to eggs, whisking constantly. Add egg mixture to remaining hot milk mixture, whisking to combine. Strain mixture through a fine-mesh sieve; discard solids.
Return mixture to pan, and cook over medium-high heat, stirring constantly until mixture is thickened, 5 to 7 minutes. Refrigerate pastry cream until cold, at least 1 hour.
In the bowl of a stand mixer fitted with the paddle attachment, combine butter, orange zest, and remaining 1/4 cup sugar. Beat at medium speed until combined. Add 1 egg and orange liqueur, and beat until combined. Gradually add salt, almond flour, and remaining 1 tablespoon cornstarch; beat until smooth, 3 to 4 minutes. Refrigerate almond cream until cool, at least 30 minutes.
In a medium bowl, combine pastry cream and almond cream. On a lightly floured surface, trim each sheet of puff pastry to an 8 1/2- or 9-inch circle. Using a fork, lightly pierce both rounds all over. Brush the edges of one round with water. Starting from the center and moving outward, pipe almond cream onto pastry round, leaving a 1-inch border all the way around. Place almond or candied fruit somewhere in the cream.
Top with second puff pastry round and press with fingertips to seal the edges. Flip galette and re-seal edges from the opposite side. Use a sharp pairing knife, cut a design on top of galette, and notch the edges. Transfer to a rimmed baking sheet.
In a small bowl, combine remaining 1 egg and remaining 1 teaspoon milk. Brush dough with eggwash, and refrigerate at least 1 hour.
Preheat oven to 400°. Bake galette for 15 minutes. Lower oven temperature to 375°, and bake until deep-golden brown, ?35 to 40 minutes. Let stand on a wire rack until cool. Brush with maple syrup, and serve.