Preheat the oven to 325F.
Line a 7"x11" baking pan with non-stick paper.
Make the cookie dough. In a bowl, whisk together the flour, baking powder and salt.
In another bowl, combine the butter with the peanut butter. Add the sugar. Whisk until smooth. Add the egg and mix until blended.
Pour the flour mixture into the butter mixture. Stir until combined. Press about three-quarters of the mixture into the bottom of the baking pan.
Place the dulce de leche and chocolate in a microwaveable bowl. Place in the microwave and heat at HIGH for about a minute. Stir until smooth.
Pour the chocolate mixture into the pan. Sprinkle with salt.
Drop in the remaining cookie dough by teaspoonfuls. Yes, on top of the chocolate.
Bake at 325F — not 350F — for 30 to 35 minutes.
Cool completely in the pan. Lift by the edges of the baking paper and transfer to a cutting board. Cut into squares or bars, whatever size you prefer.