I didn't get a lot done today, but I did finally try Lucy's Peanut Butter Brownies! Also known as Magnolia Brownies or Joanna Gaines's Brownies, this recipe has been passed down through generations. I'd be curious to know where it originated, as it also appears in the 1992 Southern Living Annual where it's called Frosted Peanut Butter Brownies. Wherever it came from, it's a basic cocoa brownie topped with a layer of peanut butter and a very sweet cocoa based frosting.

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Lucy's Peanut Butter Brownies from Magnolia and SL baked in a loaf pan.

Easy Loaf Pan Version

I would have loved to have just made the original version, but it's designed for a 13x9 inch pan and Todd and I can only eat so many brownies. My version is scaled down to fit a loaf pan and makes 8 brownies. Or maybe 16. These are super rich. But you knew that, right?

Another bonus is that the recipe is very easy and doesn't require a lot of ingredients. Plus there's a lot of passive cooling and chill time, so if you have everything but the marshmallows, you can run to the store for some.

Tips For Loaf Pan Lucy's Brownies

For this post I'm not doing an ingredient rundown. Everything is pretty straightforward, but here are a few tips.

I used an 8 ½ by 4 ½ inch loaf pan. If you use a 9x5 inch pan, the surface area will be wider and the brownies will probably be done sooner. You'll also have a thinner bottom layer. I recommend sticking with the 8 ¼ by 4 ½ inch pan.
Lucy, J. Gaines and Southern Living all make these by beating the sugar and flour together, adding the cocoa/butter mixture that, then adding the eggs last. I tried to keep things simple (and fudgy -- no risk of overbeating) by putting the sugar in with the cocoa/butter mixture then hand beating in the egg and stirring in the salt, vanilla, and flour, which is the usual method for fudgy brownies.
The old Southern Living version calls for 12 oz peanut butter while the Lucy version calls for 16. I made a quarter batch and was somewhere in the middle around 3 ½ oz. The key thing I learned was that more is not always better here, as the peanut butter could easily overpower the other components.
You only need 2 ½ marshmallows, and they do make a difference in the texture. If you have small marshmallows you could use 25.
Add the powdered sugar gradually. This frosting is very stiff and sweet, so you may need to use slightly less if you want it softer.
Update: I modified the order of ingredients in the frosting. Put the marshmallows in with the butter first. Add the other ingredients when the marshmallows are almost melted.

Other Peanut Butter Marshmallow Brownie Combos

Recipe

Frosted Peanut Butter Brownies in a Loaf Pan

Anna

Basic cocoa brownies baked in a loaf pan and topped with peanut butter and chocolate marshmallow frosting.

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Prep Time 10

Cook Time 20

Total Time 38

Course Dessert

Cuisine American

Servings

Ingredients

4 tablespoons unsalted butter (salted probably okay too)** (56 grams)
1 ½ tablespoons unsweetened cocoa powder (about 8 grams)
½ cup sugar (100 grams)
1 large egg
¼ teaspoon vanilla extract
⅛ teaspoon salt
6 tablespoons all-purpose flour (¼ cup plus 2 tablespoons) (48 grams)
¼ cup semisweet chocolate chips (optional)

Peanut Butter

½ cup creamy or crunchy peanut butter

Marshmallow Frosting

2 tablespoons unsalted or salted butter (I used unsalted) (28 grams)
2 ½ large marshmallows
1 tablespoon unsweetened cocoa powder (5 grams)
1 ½ tablespoons whole milk
1 cup sifted powdered sugar, you can use as little as ⅔ (100 grams)

Instructions

Preheat oven to 325 degrees F. Line an 8 ½ by 4 ½ inch loaf pan with a double layer of foil and grease the bottom only.
In a 1 ½ to 2 quart saucepan set over medium low heat, melt the butter, then add the cocoa powder. Stir until smooth. Add the sugar and stir just until it begins to shine. Remove from heat. Let cool slightly and beat in a cold egg. When egg is fully blended, stir in salt and flour. Let cool for about 10 minutes.
Make sure mixture is not so warm it will melt the chips, then stir in the chocolate chips.
Scrape the batter into the prepared pan and spread evenly.
Bake the brownie at 325 degrees F for 18 to 20 minutes or until the brownies' internal temperature tops out at 200 degrees F. For these, it's probably best to underbake than overbake, so be careful not to over-bake.
Remove warm brownies from the oven. Microwave peanut butter for about 30 seconds and spread over the top of the brownies. Let cool for a few minutes at room temperature, then transfer to the refrigerator and chill for another 20 minutes or until peanut butter is somewhat firm.
Prepare topping. Make sure you've already sifted and weighed your powdered sugar because it needs to be ready to go.
Clean out the saucepan you used for the brownie batter. Melt the butter and marshmallows together. When the marshmallows are very soft and almost fully melted, add cocoa powder and milk, Stir until smooth. Gradually add half the powdered sugar and begin stirring. remove from heat and stir until smooth, adding remaining powdered sugar gradually.
Stir until smooth and shiny, then pour mixture over the set peanut butter brownies. Put in the freezer for about 20 to 30 minutes (or you can just let sit at room temperature for a while), then lift from loaf pan. Trim edges and keep them for yourself, then cut the rest into 8 neat squares.

Notes

The version of this recipe in the 1992 Southern Living Annual calls for butter or margarine. Whenever I see something that says "or margarine" that's a clue that it was developed with salted butter, so if you want to try using salted butter along with the ⅛ teaspoon of salt, it should be fine.

Keyword Joanna Gaines, Lucy's Brownies, Peanut Butter Brownies

Tried this recipe?Let us know how it was!