Carrot Cake Tray Bake

A deliciously soft warmly spiced carrot cake topped with a tangy orange cream cheese frosting. Thank you Something Sweet Something Savoury

200g (1 1/4 cups) plain (all purpose) flour
1 teaspoon baking powder
1 teaspoon bicarbonate of soda (baking soda)
1/2 teaspoon fine salt
1 teaspoon ground mixed spice
1 teaspoon ground cinnamon
200ml (1 cup and 2 tablespoons) vegetable oil
200g (1 cup) soft light brown sugar
3 large eggs, at room temperature
225g (2 1/2 cups) peeled coarsely grated carrots
finely grated zest of half an orange
50g (scant 1/3 cup) roughly chopped walnuts or pecans
50g (1/4 cup) sultanas or dried cranberries (optional)

FOR THE CREAM CHEESE FROSTING
115g (1 stick) soft unsalted butter
finely grated zest of half an orange
350g (2 cups + 1 tablespoon) icing (confectioners') sugar
125g (1/2 cup) fridge cold full fat cream cheese
25g chopped walnuts, for decoration (optional)
1 teaspoon orange zest, for decoration (optional)

• Preheat the oven to 180C/160Fan/350F. 
• Grease and line a 9x13 (33 x 22.8 x 5cm) baking pan with baking parchment.
• Place the flour, baking powder, bicarbonate of soda, salt, mixed spice and ground cinnamon in a large bowl 
• Stir well until well combined.
• Place the oil, brown sugar, and eggs in another large bowl 
• Using a whisk or fork, mix well until the mixture is smooth and there are no large lumps of sugar.
• Add the dry ingredients to the oil mixture 
• Using a wooden spoon or rubber spatula, stir well until evenly combined. 
• Take care not to overmix the batter.
• Fold in the carrots, orange zest, chopped walnuts or pecans and sultanas or cranberries (if using.) 
• Pour the mixture into the lined tin and bake in the oven for 40-45 minutes or until golden, risen and a skewer or cocktail stick inserted in the centre of the cake emerges clean.
• Leave the cake to cool in the tin for 10-15 minutes
• Turn out onto a wire rack to cool completely.
• Once the cake has cooled, make the cream cheese frosting. 
• Using an electric mixer, beat the butter, orange zest and the icing sugar together until creamy and smooth, 
• Beat in the cold cream cheese until you have a smooth, fluffy icing, about 2-3 minutes 
• Don't overbeat at this stage or the frosting could turn too runny.)
• Place the cold cake on a serving plate and spread with the cream cheese frosting.
• Sprinkle with a little chopped walnuts and orange zest, if desired.