Chai spiced carrot cake

Name: Chai spiced carrot cake
Ingredients: 250ml vegetable oil, plus extra for greasing; 4 large carrots; 1 large lemon; 100g currants or sultanas; 100g pecans; 280g plain flour; 2 teaspoons baking powder; 1 tablespoon ground ginger; 1 tablespoon ground cinnamon; 2 teaspoons ground cardamom; ¼ teaspoon ground cloves; ¼ teaspoon ground anise; ¼ teaspoon ground nutmeg; 4 tablespoons candied ginger in syrup; 1 black tea bag; 2 large free-range eggs; 200g caster sugar; 200g light brown sugar; 30g flaked coconut; CREAM CHEESE BUTTERCREAM; 200g unsalted butter (at room temperature); 200g cream cheese; 125g icing sugar