Go Back

Monster Bars

These monster bars feature all of the classic flavors of a beloved monster cookie but baked in bar form. Peanut butter with chocolate is a dessert combo that is always a hit!
5 from 2 votes
Course Cookies and Bars
Cuisine American
Servings 48 bars


  • ½ cup (1 stick) butter
  • 1 ¼ cups peanut butter
  • 1 cup sugar
  • 1 cup brown sugar
  • 3 eggs
  • 2 teaspoons corn syrup
  • 2 teaspoons vanilla
  • ½ teaspoon salt
  • 2 teaspoons baking soda
  • 4 ½ cups old-fashioned oats
  • 1 ½ cups semi-sweet chocolate chips
  • 1 10- oz bag or closest size mini M&Ms, reserving about ¼ cup


  • Cream the butter, peanut butter, and sugars together with a mixer for 2-3 minutes or until fluffy. Add eggs, corn syrup, vanilla—mix until well combined. Then mix in salt and baking soda.
  • By hand, stir in the oats, chocolate chips, and mini M&Ms until completely combined. Save ¼ cup of the mini M&Ms to top the bars. Cover the dough and refrigerate at least 2 hours (this is not required but your dough will be less sticky).
  • When ready to bake, preheat oven to 350°. Grease or line two 9x13 inch pans with parchment paper. Spread half the cookie dough into each pan. Press down slightly and sprinkle the remaining M&Ms on the top of each pan. Bake approximately 22-25 minutes or until lightly golden and still fairly soft. The time varies depending on the placement in the oven and type of pan used, so watch carefully. Generally, baking with glass pans takes a little longer.
  • Let cool slightly on a wire rack before cutting. These are especially delicious while the chocolate is still melty!


The dough or baked bars freeze wonderfully. It works well save half the dough or one baked pan in the freezer for later use. Be sure to wrap tightly before freezing.