Step 1

Heat the oven to 325°F with a rack in the middle position. Coat a 9-by-5-inch loaf pan with cooking spray, dust evenly with flour, then tap out the excess. In a 2-cup liquid measuring cup or small bowl, beat the eggs and vanilla until combined; set aside.

Step 2

In a stand mixer fitted with the paddle attachment, mix the 241 grams sugar and the lemon zest on low until fragrant, about 1 minute. Add both flours, the baking powder and salt and mix until combined, about 10 seconds. With the mixer on low, add the butter a piece at a time. Once all the butter has been added, continue mixing on low until the mixture is crumbly and no powdery bits remain, 1 to 2 minutes.

Step 3

With the mixer still running, add the egg mixture in a slow, steady stream and mix for about 10 seconds. Increase to medium-high and beat until the batter is light and fluffy, 1 to 1½ minutes, scraping the bowl once or twice. The batter will be thick.

Step 4

Transfer the batter to the prepared pan and smooth the surface, then sprinkle evenly with sliced almonds. Bake for 45 minutes, then reduce the oven to 300°F. Continue to bake until the top is deep golden brown and a toothpick inserted at the center of the cake comes out clean, another 30 to 35 minutes.

Step 5

While the cake is baking, in a small saucepan over medium-low, heat the remaining 54 grams sugar and 2 tablespoons of lemon juice, stirring often, until the sugar dissolves and the mixture reaches a simmer. Immediately remove from the heat and stir in the remaining 1 tablespoon lemon juice. Set aside to cool.

Step 6

When the cake is done, cool in the pan on a wire rack for 10 minutes. Invert the cake onto the rack, then turn it upright. Using a toothpick, poke small holes in the surface at 1-inch intervals. Brush all of the lemon-sugar syrup onto the cake, allowing it to soak in. Cool completely before slicing, about 2 hours.