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4.73 from 11 votes

Oatmeal Peanut Butter Bars


  • 2 1/3 cups old fashioned oats
  • 1 1/2 cups flour
  • 1 tsp baking powder
  • 1 cup creamy peanut butter
  • 1 cup butter (softened)
  • 2/3 cup white sugar
  • 1 1/3 cup brown sugar
  • 2 eggs
  • 1 tsp vanilla
  • 1/2 tsp salt

For topping the bars:

  • 1 cup peanut butter
  • 1/2 cup butter
  • 6 TBS milk (whole or 2%)
  • 4 TBS cocoa powder
  • 3 1/2 cups powdered sugar


  • Preheat the oven to 375 degrees Fahrenheit. Line a rimmed half cookie sheet (13x18x1) with parchment paper, or spray with nonstick spray. 
  • In a large bowl, combine the old fashioned oats, flour, baking powder, and salt. Set aside.
  • In a large mixing bowl, mix together your peanut butter and butter. 
  • Add in the sugar and brown sugar and cream together till smooth, and light. 
  • Add in the eggs, and vanilla and stir to combine. 
  • Add the dry ingredients to the wet ingredients and stir it all together. 
  • Press the cookie dough into the cookie sheet, spreading evenly to the edges. The dough is pretty sticky, so spray your hands or a rubber spatula with nonstick spray while you spread it. 
  • Bake in the preheated oven for 15 minutes, until the middle is just barely set. 

For Topping the Bars:

  • Allow the bars to cool for about 5 minutes, then drop peanut butter dollops over the top of the bars. 
  • Allow to sit for about 1-2 minutes until the peanut butter starts to soften, then spread the peanut butter evenly over the top. 
  • In a medium sized heavy sauce pan over medium heat, add butter, cocoa powder and milk. Bring to a boil.
  • Remove from heat and whisk in powdered sugar till smooth.
  • Spread chocolate frosting over the top of the bars and spread into an even layer. 
  • Allow frosting to set and bars to cool completely before cutting into squares to enjoy. 
  • Store bars in an airtight container at room temperature for 5-6 days.