Preheat the oven to 400 degrees F while you set your baking pan with parchment paper or a buttered sheet.
Take a bowl and start mixing flour, salt, baking soda, and sugar.
Separate 2 tbsp from the milk quantity and add the remaining to another bowl. Add the vanilla essence, and eggs, and mix it well.
Take a saucepan in which melt 1 cup of the butter only and 1 cup of peanut butter. Add the dry ingredients and then the milk and egg mixture. Make sure to mix it well and then pour it hot on the baking sheet.
Spread it evenly with the help of a spoon or spatula. Bake it for 20-22 minutes.
Make the frosting by adding the remaining peanut butter, butter, 2 tbsp milk, and powdered sugar. Add it as the top layer and then let your dessert cool. Serve it with your favorite toppings.