Preheat the oven to 180°C (350°F). Grease a 9-inch (23 cm) springform or round cake pan and line the base with parchment paper, using Butter to coat the pan so the cake releases easily.
In a large mixing bowl, whisk the Eggs together with the Granulated Sugar until the mixture is pale, thick and slightly increased in volume (about 4–6 minutes by hand or 2–3 minutes with a mixer).
Add the finely grated zest of one Lemon and a teaspoon of Ground Cinnamon to the egg-sugar mixture and stir to combine, which will give the cake its characteristic aromatic lift.
Fold in the Ground Almonds and then gently mix in about 60–80 g of melted butter (warm but not hot) until the batter is homogeneous and slightly thick—avoid overmixing to keep the texture tender.
Pour the batter into the prepared pan, smooth the top with a spatula, and tap the pan once on the counter to remove any large air bubbles.
Bake in the preheated oven for 30–40 minutes, or until the top is golden and a skewer inserted into the center comes out clean or with a few moist crumbs but not wet batter.
Allow the cake to cool in the pan for 10–15 minutes, then remove the springform rim and transfer the cake to a wire rack to cool completely. Once cool, dust the top generously with Powdered Sugar; traditionally a cross stencil can be used for decoration if desired.
Slice and serve at room temperature with coffee or a sweet wine. The cake keeps well for 2–3 days stored in an airtight container.
