Best ever carrot cake

• 160 g extra virgin olive oil, plus extra to grease
• 250 g walnuts
• 400 g carrots, cut into pieces
• 2 eggs
• 220 g raw sugar
• 1 tsp vanilla essence
• ½ tsp mixed spice
• ¼ tsp sea salt
• 200 g plain flour
• 1 tsp bicarbonate of soda

Frosting

• 120 g raw sugar
• 90 g cream cheese
• 30 g butter, softened
• ¼ tsp freshly squeezed lemon juice