Tarta de Santiago — Galician almond cake

Preheat the oven to 175°C with top and bottom heat, without convection, and position the rack in the middle. Prepare a 22 cm springform pan at least 5 cm tall, a scale, a hand whisk, a spatula, a fine sieve and a cooling rack. Line the base with parchment paper, clamping it in the ring, and line the sides with a fitted strip of paper about 5 cm tall. The paper separates the cake from the pan, so no fat is needed for greasing. From a separate clean piece of parchment, cut a flat Saint James cross stencil about 12 cm tall and about 8 cm wide: the lower arm is long and ends in a sword point, while the shorter top and side arms have fleur-de-lis ends. Set the stencil aside for decorating.

Wash and dry the lemon, grate only the yellow layer of zest and weigh out 4 g. Do not add the juice or the rest of the fruit to the cake. Crack all 5 eggs into a large bowl; their contents should weigh about 250 g. Use the whites and yolks together. In a separate bowl, mix the 250 g of ground almonds with 0.5 g of cinnamon, rubbing out lumps with your fingers. The almonds should resemble fine meal, with no large pieces and no oily paste texture. Weigh out the 250 g of superfine sugar and 15 g of powdered sugar separately.

Add all 250 g of superfine sugar and the 4 g of lemon zest to the bowl of eggs. Stir with a hand whisk for about 2–3 minutes, until the whites and yolks combine with the sugar, the mixture becomes slightly paler and a thin layer of fine foam appears on the surface. You do not need to dissolve every sugar crystal. Stop mixing at this stage; do not beat the eggs into a very fluffy foam several times their original volume.

Add the almonds and cinnamon in 2 batches, folding from the bottom with a spatula after each addition, just until combined. Scrape down the sides of the bowl. The batter should be thick and finely grained and flow from the spatula in a broad ribbon; do not add flour, liquid or baking powder. Transfer all of it to the prepared springform pan and level the surface. The layer will be about 2 cm deep. Gently tap the pan once on the counter to remove large air bubbles and immediately place it in the preheated oven.

Bake at 175°C for about 35–45 minutes. Do not open the oven during the first 30 minutes. Start checking after 35 minutes: the top should be evenly golden, the edges slightly darker and the center stable when you gently move the pan. A wooden skewer inserted into the center may have a few moist crumbs on it, but not wet, raw batter. If the center is still underbaked, bake for another 3–5 minutes at a time and check again. If the top browns too quickly, cover it loosely with aluminum foil for the final part of baking. Small cracks and a slight settling after removal from the oven are natural. Place the finished cake in its pan on the rack.

Leave the cake in the pan for 20 minutes. Carefully open the ring and remove the side strip of paper, leaving the cake on the springform base. Cool on the rack for about another 100 minutes, until the center and underside are completely cool as well. Allow longer cooling in a warm room; powdered sugar dissolves quickly on a warm cake. Only once the cake is cold, support it with wide spatulas, lift it off the pan base, carefully remove the paper underneath and transfer to a flat plate. The cake should remain low, about 2–3 cm tall.

Lay the prepared stencil flat in the center of the cold cake, with the long blade of the cross pointing down. Put the measured 15 g of powdered sugar into a fine sieve and sift a thin, even layer over the entire top, including the stencil. Some sugar will remain on the paper and plate. Carefully grasp the stencil at opposite ends and lift it vertically, without sliding it over the cake and without shaking sugar onto the exposed design. A golden cross should remain against a white background. Do not add the sugar from the stencil or from outside the cake back onto the top.

Cut the completely cooled cake into 10 equal wedges with a sharp knife, wiping the blade between cuts. Lift the slices with a wide spatula so you do not break up the moist almond crumb. Each serving should show a finely grained, golden cut surface and a thin layer of powdered sugar on top. Serve at room temperature. If preparing the cake ahead, store it covered and dust with sugar only just before serving, so the design stays clear.