Coffee, sour cream and walnut cakes

Ingredients

• Cakes
• 100 grams soft butter
• 2/3 cup (about 100g) brown sugar, loosely packed
• 3 eggs
• 50 grams sour cream
• 50 grams walnut, chopped, plus extra pieces to garnish
• 1 1/2 cup plain flour (or 1 1/4 cups gluten-free flour)
• 3 teaspoons baking powder
• 3 teaspoons fine-ground espresso or 2 tsp instant coffee
• 1 tablespoon (1-2 tbsp) milk
• Icing
• 100 grams cream cheese
• 2 tablespoons sour cream
• 1/2 cup brown sugar
• 2 tablespoons (heaped tbsp) icing sugar