Preheat the oven to 375°F. Line a 13x9-inch baking pan with parchment or foil and spray with nonstick cooking spray.
In large bowl, use an electric mixer to beat the butter, milk and brown sugar until well combined and smooth. Add the egg and vanilla and beat until fully combined. Slowly beat in the malted milk powder, flour, salt and baking soda.
Press cookie dough into prepared baking pan. Bake for about 15 minutes, or until lightly browned. Remove from oven and set on a cooling rack to cool completely.
Meanwhile, in large saucepan set over medium-low heat, heat the condensed milk and butter until the butter is melted and the mixture is warmed. Remove from heat and add the chocolate, stirring until melted and smooth. Pour over cooled cookie crust.
In a microwave safe measuring cup or small bowl, heat the peanut butter for 30 seconds, or until melted and thin. Drizzle over fudge filling. Immediately press the chocolate covered pretzels into the bars. Refrigerate cookies for 2 hours or overnight before cutting into bars and serving.