Before you begin preheat the oven to 300ºF/150ºC. Spread the ground almonds onto a baking sheet and toast for 8-10 minutes until just beginning to color and smell nutty. Set aside to cool.
Increase the temperature to 350ºF/180ºC and butter a 9 inch/23 cm springform pan then line the base with parchment paper.
In a small bowl, rub the lemon zest into the sugar with your fingers and set aside.
Beat the eggs and the sugar with an electric mixer until the mixture it becomes pale and thick and is well combined (6-8 minutes). Don’t use the whisk attachment
Mix in the cooled almond meal, ground cinnamon and brandy.
Pour the batter into a buttered and floured cake pan.
Bake for 30-35 minutes until the surface is browned and when a skewer is inserted it comes out clean.
Cool the cake in the pan.
When cooled, unmold and dust thickly with powdered sugar.