Chocolate cake with avocado and pistachios

Ingredients

• 2 avocados (divided)
• 1 3/4 oz pistachios (chopped)
• 2 cups flour
• 3/4 cup ground almonds
• 3/4 cup cane sugar
• 1/2 cup cocoa powder
• 1 tsp baking powder
• 1 tsp baking soda
• 1/2 tsp salt (divided)
• 2 tbsp apple cider vinegar
• 50 ml vegetable oil
• 1 cup almond milk
• 1/4 cup sparkling water
• 1/2 tsp lemon juice
• 1/2 tsp vanilla extract
• 2 cups confectioner's sugar
• margarine for greasing
• flour for dusting