Step 1
Preheat the oven to 165C fan-forced (185C conventional) and line the base and sides of a 20cm cake tin with baking paper.
Step 2
Combine the citrus zests, vanilla seeds (if using) and sugar in the bowl of an electric mixer and use your fingertips to rub the zest and vanilla seeds into the sugar. Rub firmly for 1–2 minutes until the sugar is tinged yellow and orange and smells divine.
Step 3
Add the butter and attach the bowl to the mixer and beat with the paddle attachment on medium speed for about 2 minutes, until the mixture is light and creamy. Add the eggs one at a time, scraping the sides of the bowl with a flexible spatula after each addition. Pause the beating while you get the dry ingredients ready.
Step 4
Sift the flour, baking powder and salt into a bowl, then stir in the almonds. Add about half of the dry ingredients to the butter mix and beat on a low speed for a few seconds, then add the lemon and orange juice. If using vanilla extract, add it now. Mix for a few seconds to incorporate, then add the rest of the dry ingredients and beat until just combined.
Step 5
Scrape the batter into the prepared tin and level the top with a small spatula. Place in the oven for 55–60 minutes, or until a skewer inserted into the middle of the cake comes out dry. Transfer to a wire rack to cool completely.
Step 6
To make the glaze, combine the icing sugar, lemon and orange juice and mix to a smooth paste.
Step 7
When the cake is completely cool, remove it from the tin and pour the glaze into the middle of the cake, allowing it to spread to the edges. Garnish, if desired, with a few slices of orange and lemon placed in the centre.
