1. Preheat oven to 350 degrees. Place a 9 1/8-by-1 3/8-inch tart ring on a baking sheet lined with parchment; set aside. On a lightly floured surface, roll out 1 disk of dough to 1/8 inch thick; cut into a 14-inch round. Fit into tart ring; trim overhang to 1/2 inch. Refrigerate while making filling.

2. Whisk together 4 eggs, the honey, granulated sugar, butter, orange zest and juice, salt, and flour in a large bowl. Stir in walnuts. Pour into tart shell.

3. On a lightly floured surface, roll out remaining disk of dough to 1/8 inch thick. Cut into an 11-inch round. Cut 5 slits for vents. Drape over filling. Trim overhang to 1 inch; fold over bottom crust. Press edges to seal, and tuck into ring. Brush with remaining beaten egg, and sprinkle with sanding sugar.

4. Bake until a knife inserted in one of the vents comes out clean, 45 to 50 minutes. Transfer sheet to a wire rack; let cool completely. Remove ring before serving. Can be stored, covered, overnight.