Plan Ahead: For best flavor, complete the cake 1 day ahead.
Preheat the Oven: Twenty minutes or more before baking, set an oven rack in the lower third of the oven and preheat the oven to 350°F/175°C (325°F/160°C if using a dark pan).
Toast and Grind the Almonds: Spread the almonds evenly on a baking sheet and bake for about 7 minutes, or until pale gold. Stir once or twice to ensure even toasting and avoid overbrowning. Cool completely. In a food processor, process until fairly fine. Add 1/4 cup of the sugar and process until very fine.
Mix the Liquid Ingredients: In a medium bowl, whisk the eggs, 1/4 cup of the sour cream, the vanilla, and lemon oil just until lightly combined.
Make the Batter: In the bowl of a stand mixer fitted with the flat beater, mix the ground almonds, the remaining sugar, the flour, baking powder, baking soda, salt, and lemon zest on low speed for about 30 seconds. Add the butter and the remaining sour cream. Mix on low speed until the dry ingredients are moistened. Raise the speed to medium and beat for 1 1/2 minutes. Scrape down the sides of the bowl.
Starting on medium-low speed, gradually add the egg mixture in two parts, beating on medium speed for 30 seconds after each addition to incorporate the ingredients and strengthen the structure. Using a spatula or spoon, scrape the batter into the prepared pan and smooth the surface evenly with a small metal spatula.
Bake the Cake: Bake for 45 to 55 minutes, or until a wooden toothpick inserted between the tube and the side comes out clean and the cake springs back when pressed lightly in the center. An instant-read thermometer inserted near the center should read 200° to 205°F/93° to 96°C.
Make the syrup shortly before the cake is finished baking.
Make the Lemon Syrup: In a 1-cup or larger microwavable glass measure (or a small saucepan over medium heat), heat the sugar and lemon juice, stirring often until the sugar is almost completely dissolved. Do not boil. A few undissolved grains form a sparkly, crackly finish to the crust. Cover it tightly to prevent evaporation.
Apply the Syrup and Cool and Unmold the Cake: As soon as the cake comes out of the oven, place the pan on a wire rack, poke the cake all over with a thin skewer, and brush it with about one-third of the syrup. Let the cake cool in the pan for 10 minutes. Invert it onto a 10-inch cardboard round or serving plate. Brush the top and sides of the cake with the remaining syrup. Cool completely and wrap airtight.
Variation: Golden Gift Lemon Almond Cake: Make two-thirds of the batter, but use 3/4 teaspoon baking powder and 1/2 teaspoon of baking soda. Bake for 40 to 50 minutes. Make two-thirds of the syrup. When cool, wrap the cake in holiday-tinted plastic wrap and tie the package with a bow. This cake serves 8 to 10.
Reprinted from Rose's Heavenly Cakes by Rose Levy Berenbaum. Copyright © 2009 Published by Wiley.
Andrea Reusing is the creator of the restaurant Lantern in Chapel Hill, N.C., and author of the book Cooking in the Moment: A Year of Seasonal Recipes. In this installment of The Key 3, she shares with Lynne Rossetto Kasper the techniques behind three of her favorite recipes: Turnip Soup, Overnight Braised Short Ribs and Tomato Salad.