Preheat the oven to 160C/320F and lightly greaseproof a loaf tin.
Place the sugars, oil and eggs and whisk until well combined, approximately 2 minutes.
In a separate bowl place the flour, baking soda, baking powder and ground spices and stir to combine.
Toss the dry ingredients into the wet ingredients and fold until your cake batter is formed and no dry portions remain on the edges of your bowl.
Really fold here because the wet ingredients will sneakily puddle up in spots and the batter will be quite thick by the time you have finished incorporating.
Add the grated carrot and roughly chopped walnuts and fold until well combined.
Pour into your loaf tin and smooth out on top.
Bake until golden and a skewer comes out clean, approximately 1 hour 5 minutes.
Remove and allow to cool for 10 minutes before placing on a cooling rack to cool completely.