Start by preheating your oven to 350°F (175°C). Line your 9x9 inch baking pan with parchment paper, leaving some overhang on the sides for easy removal later.
In a mixing bowl, cream together the softened butter and 1/3 cup of powdered sugar using an electric mixer. Beat in 1 teaspoon of vanilla extract until fully incorporated. Gradually add in the all-purpose flour and salt. Mix until the dough comes together.
Spread the cookie dough evenly into the prepared baking pan. Bake in the preheated oven for 15-18 minutes or until lightly golden. Remove from the oven and let it cool completely in the pan.
In a separate bowl, combine the creamy peanut butter with the remaining 1/2 cup of powdered sugar and the remaining teaspoon of vanilla extract. Mix until smooth and creamy.
Once the cookie base is cool, spread the peanut butter mixture evenly over the top. Make sure to cover the entire surface for a balanced flavor in every bite.
In a double boiler or microwave-safe bowl, combine the milk chocolate chips and Crisco shortening. Melt the chocolate gently, stirring until smooth and fully combined.
Pour the melted chocolate over the peanut butter layer, spreading it evenly with a spatula. Make sure to cover all the edges to seal in the deliciousness.
Refrigerate the assembled bars for at least 1 hour or until the chocolate is set. Once firm, use the overhanging parchment paper to lift the bars out of the pan. Cut into squares or rectangles, and indulge!
