Preheat the oven to 180°C. Grease a 23cm x 13cm loaf tin with butter and line the base and sides with baking paper. Set aside.
In a large mixing bowl, combine the sugar, bergamot zest and orange zest. Using your fingertips, rub the zest into the sugar until fragrant and the sugar feels like wet sand.
150 g granulated sugar, Zest from 2 bergamots, Zest from 1 orange
Add the olive oil, eggs, bergamot juice and orange juice and whisk until well combined.
240 ml olive oil, 3 eggs, 70 ml bergamot juice, 110 ml orange juice
Add the flour, baking powder and salt. Fold gently until just combined and no streaks of flour remain. Do not overmix.
280 g all-purpose flour, 1 teaspoon baking powder, ¼ teaspoon salt
Pour the batter into the prepared loaf tin and bake for 50–60 minutes, or until a metal skewer inserted into the centre comes out clean.
Allow the cake to cool completely before making the drizzle.