Using a flexible rubber spatula, fold in almond flour, walnuts, cinnamon, and nutmeg until combined. Fold in grated apple. Pour batter into prepared pan and gently tap on the counter to evenly distribute. Bake until golden brown and top of cake bounces back to the touch, about 50 minutes.

While cake is still warm, loosen exposed short sides of cake from pan using an offset spatula or butter knife. Using parchment paper as a handle, lift cake out of pan and onto a cutting board. Cut cake into diamond shapes by making a series of diagonal slices in one direction across the cake, then making another series of diagonal slices in the opposite direction. Lift sliced cake, again using parchment, and return to pan. Strain syrup over warm cake using a fine-mesh strainer, then let sit at least 1 hour to allow cake to fully absorb syrup. Serve.

Special equipment
9-by-13-inch anodized aluminum baking pan, medium nonreactive saucepan or saucier, stand mixer, instant-read thermometer, fine-mesh strainer.

Though it’s commonly served at Passover, when flour and leavening action are forbidden, I like it any time I need a gluten-free dessert. This is my Americanized version: a heady mix of spices and citrus, with grated apple added to the traditional nut-based cake. Rather than rose blossom syrup, I opt for a ginger-infused syrup that’s boozy with Applejack, America’s own apple brandy.
For the Syrup:
1 cup sugar (7 ounces; 200g)
1 1/2 cups unsweetened apple juice (12 ounces; 340g)
2-inch piece ginger (2 ounces; 60g), unpeeled, cut in half lengthwise and smashed
Zest from 1 medium lemon
1 tablespoon fresh lemon juice (1/2 ounce; 14g), from about 1 lemon
4 tablespoons Applejack brandy (2 ounces; 60g)
For the Cake:
4 large eggs (6.8 ounces; 190g)
3/4 cup sugar (5 3/4 ounces; 160g)
1 teaspoon (4g) Diamond Crystal kosher salt; for table salt, use about half as much by volume or the same by weight
1 cup vegetable oil (8 ounces; 220g), or any other neutral oil
2 tablespoons freshly grated ginger (1 ounce; 30g)
2 1/2 cups almond flour (8 ounces; 230g)
1 1/2 cups finely chopped walnuts (6.2 ounces; 175g)
2 teaspoons (6g) ground cinnamon
1/4 teaspoon freshly grated nutmeg
2 cups grated unpeeled Fuji apple (12 ounces; 340g), from about 2 medium apples