Chocolate Peanut Butter Cookie Sandwiches

Cookies

• 210 g smooth peanut butter (see tip)
• 200 g soft dark brown sugar
• 1 medium egg
• 2 Tbsp cocoa powder (see tip)
• 1 tsp gluten-free baking powder
• 1 tsp natural vanilla extract

Filling

• 40 g unsalted butter soft
• 25 g smooth peanut butter
• 80 g icing sugar
• ½ tsp vanilla extract
• ½ tsp milk