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Fudgy Oat Brownies

These cakelike brownies have a rich, crunchy oat crust and a smooth homemade chocolate frosting. A packaged brownie mix makes the recipe easy to prepare. You can make it even easier by using canned frosting. —Diana Otterson, Canandaigua, New York
  • Total Time
    Prep: 30 min. Bake: 35 min. + cooling
  • Makes
    3 dozen


  • 1-1/2 cups quick-cooking oats
  • 3/4 cup all-purpose flour
  • 3/4 cup packed brown sugar
  • 1/4 teaspoon baking soda
  • 1/4 teaspoon salt
  • 3/4 cup butter, melted
  • 1 package fudge brownie mix (13x9-inch pan size)
  • 3 tablespoons butter
  • 1-1/2 ounces unsweetened chocolate
  • 2-1/4 cups confectioners' sugar
  • 3 to 4 tablespoons hot water
  • 1-1/2 teaspoons vanilla extract


  • In a large bowl, combine the oats, flour, brown sugar, baking soda and salt. Stir in butter until combined. Press into an ungreased 13x9-in. baking pan. Bake at 350° for 10-11 minutes or until puffed and edges are lightly browned.
  • Meanwhile, prepare brownie mix according to package directions for cakelike brownies. Spread batter over crust. Bake 25-30 minutes longer or until a toothpick inserted in the center comes out clean.
  • For frosting, in a microwave-safe bowl, melt butter and chocolate; stir until smooth. Immediately stir in the confectioners' sugar, 2 tablespoons water and vanilla until smooth. Add remaining water as desired; stir until smooth. Immediately spread over brownies. Cool on a wire rack until firm. Cut into 36 bars.
Nutrition Facts
1 brownie: 217 calories, 11g fat (4g saturated fat), 29mg cholesterol, 131mg sodium, 29g carbohydrate (20g sugars, 1g fiber), 2g protein.
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  • karenbecca25
    Sep 18, 2017

    I love the oat crust. And the homemade frosting beats any store bought frosting hands down!

  • 2124arizona
    Apr 8, 2017

    Absolutely super moist brownies!!!

  • HeatherHH
    Mar 10, 2017

    I found these to be quite good, but not as outstanding as they'd need to be for me to remake them with the extra work. I have a frosted brownie recipe that I much prefer.

  • meliss.beyer
    Mar 8, 2015

    These brownies are always a hit! They are easy to make especially using your favorite brownie mix. Sometimes I cheat and use bought chocolate frosting that I melt a little before spreading on.

  • Bikerbaker
    Oct 9, 2014

    I made these today at my work, which is a private lodge and I supply a lunch dessert daily. I am always on the lookout for brownie variations. These were delicious! very unique, to have an oat cookie base. I made my own favorite brownie recipe to top them, and a whipped ganache for the frosting. I needed a large amount, so I doubled all ingredients. Thank you for a great recipe!

  • mamoonis
    Aug 16, 2014

    Used the Five Star Brownie recipe here instead of a mix. AWESOME!!

  • Kirstenbultman
    Jul 8, 2014

    These were so indulgent. I added chocolate chips to the brownie batter and frosted with peanut butter frosting. They looked very pretty and tasted even better. Great way to jazz up a boxed brownie mix. A winner!

  • delowenstein
    Jun 29, 2014

    I recall preparing these brownies when they appeared in the 2005 Brownie Contest for Taste of Home! I'd greased and floured my baking pan (13x9x2") and I'd used 3-1/4 cups of confectioners' sugar! I plan to use this recipe again! It's a great recipe to use and for me, it's a keeper! delowenstein

  • Danerlea
    Feb 21, 2012

    Everyone LOVES these brownies. They disappear in a flash!

  • khudgin
    Aug 22, 2011

    This is my all time favorite brownie recipe! I make them a lot for our youth group or church events and I never come home with left overs!