Persimmon and walnut scones

Ingredients

• 1 persimmon
• 1 1/2 oz walnuts
• 2 cups flour
• 1/4 cup sugar
• 2 tsp baking powder
• 1/2 tsp baking soda
• 1/2 tsp salt
• 1/2 tsp ground cinnamon
• 1/4 tsp ground cardamom
• 7 tbsp unsalted butter (cold)
• 1/2 cup buttermilk
• 1/2 tsp vanilla extract
• 1 egg
• 2 tbsp heavy cream
• flour (for dusting)
• sugar (for sprinkling)
• confectioner’s sugar (for serving)