Fudgy Peanut Butter Slice - Bake with Amy

Ingredients

• 150 g plain cookies, finely crushed (1 1/2 cups)
• 130 g icing sugar (1 cup)
• 375 g commercial smooth peanut butter (1 1/2cups)
• 115 g unsalted butter, melted (1/2 cup)
• 1 tsp vanilla extract
• ¼ tsp fine salt
• 255 g dark or milk chocolate chips
• 4 tbsp commercial smooth peanut butter
• 2 tbsp commercial smooth peanut butter (for swirls, optional)