Step 1Spread almonds for both filling and dough on baking sheet and toast at 325 degrees until lightly browned, 15 to 20 minutes. Shake pan halfway through to ensure nuts are evenly toasted. Allow nuts to cool. Set aside 1/3 cup nuts for dough.
Step 2Combine 1/4 cup plus 2 tablespoons almonds with powdered sugar in bowl of food processor fitted with metal blade. Process until it is the consistency of a fine meal. Add cardamom, cinnamon and nutmeg and pulse to combine. Transfer to a bowl. Make a well in center and pour in 2 egg whites. Gradually draw in dry ingredients and whisk until thoroughly incorporated. Mixture should be shiny, smooth and spreadable. If it seems too stiff, add a few drops of the extra egg white. Set aside.
Step 1Combine almonds and half powdered sugar in bowl of food processor and process until it's the consistency of a fine meal. Add remaining sugar, flour, baking powder and salt and pulse a few times to combine. Add butter and pulse on and off until it's the consistency of a fine meal, 30 seconds.
Step 2Whisk together egg yolks, cream and orange flower water in small bowl. Add flour mixture and pulse until the dough barely comes together.
Step 3Turn dough out onto a lightly floured work surface. Dip heel of your hand in flour and, working with small sections, smear dough away from you to blend it together. When dough has been all smeared out, use a metal scraper or spatula to scrape and gather it together. Divide dough in half and gently knead each half together. Flatten into 2 (3x5-inch) rectangles, wrap in plastic and chill until firm, at least 2 hours or overnight.
Step 1Remove half the dough from refrigerator and turn onto lightly floured surface. Roll dough into 13x5-inch rectangle about 1/4 inch thick and transfer to parchment-lined baking sheet. Use a rule to trim edges so dough is 12x4 inches.
Step 2Using an offset spatula or back of a spoon, spread orange marmalade evenly over dough. Spread Nut Filling over marmalade. Chill bottom while you roll out remaining dough.
Step 3On a lightly floured surface, roll remaining half of dough into 15x6-inch rectangle, 1/8 inch thick. Cut dough into 12 strips, 3/4 inch wide. Remove bottom from refrigerator. Layer 6 strips diagonally across filling, at 1-inch intervals, using shorter pieces toward short ends of rectangle. To form second layer of lattice, place remaining strips over first layer, crisscrossing diagonally.
Step 4Trim strips with knife and cut dough into 8 equal slices. Chill 30 minutes.
Step 5Bake at 350 degrees until nicely browned, 40 minutes.