FOR THE CAKE – 1 stick of salted butter [113 grams, 4 ounces] at room temperature, plus extra to grease the pan – 1 cup of all-purpose flour [120 grams, 4.2 ounces], plus extra to dust pan – ½ teaspoon of baking soda – ½ cup of sugar (white, granulated) [200 grams, 7.1 onces] – 2 egg of (medium), at room temperature – 4 tablespoons of mandarin juice – ¼ teaspoon of mandarin zest FOR THE SYRUP – The rind of a quarter of a mandarin orange – 1 cup of mandarin juice – ¼ cup of powdered sugar – Seeds of ½ vanilla pod, or 1 teaspoon of vanilla extract