175g softened unsalted butter, chopped
3/4 cup (165g) caster sugar
1 tbsp milk
1 cup (150g) self-raising flour, sifted
1/2 cup (60g) almond meal
3/4 tsp ground cinnamon
1/4 cup (35g) icing sugar, sifted
2 tbsp Grand Marnier or other orange-flavoured liqueur
Whipped cream, to serve
1 1/2 cups (330g) sugar
2 oranges, thinly sliced
Preheat the oven to 180°C. Grease an 18cm round spring-form cake pan and line the base and sides with baking paper.
Beat the butter and caster sugar with electric beaters until thick and pale. Add the eggs, 1 at a time, beating well after each addition, then beat in the milk and zest and juice of 1 orange. Combine the flour, almond meal and cinnamon in a separate bowl, then fold into the egg mixture until well combined. Pour the batter into the pan, then bake for 45 minutes or until a skewer inserted into the center comes out clean. Cool the cake in the pan for 15 minutes.
Meanwhile, for the candied orange, place sugar in a saucepan with 2 cups (500ml) water and bring to the boil over high heat, stirring until sugar dissolves. Add orange and cook for 10 minutes or until softened and translucent. Transfer the orange to a baking tray lined with baking paper, discarding the syrup.
To make drizzle, combine icing sugar, Grand Marnier and juice of remaining 3 oranges in a saucepan. Bring to the boil, then reduce heat to medium-low and cook for 5-6 minutes until the syrup is reduced by half, thick and glossy.
Prick the top of the cake all over with a skewer, then pour over half of the drizzle. Top with candied orange, then pour over the remaining drizzle. Serve with the whipped cream.