I love an easy bar cookie, don’t you? These endlessly adaptable marshmallow bars are even better, because I get to use up the remnants of an open jar of jam. These cookies are inspired by and adapted from Joy the Baker – and they remain a favorite in my family. They’re cookielicious! January 2022: I’m editing this post and re-publishing, because I’ve made some very helpful changes, streamlining the recipe significantly.

The absolute best thing about them is that they’re so flexible. They start with a shortbread cookie base, and they end up with browned (toasted) marshmallows – but what goes between is entirely up to you. Want chocolate? Then add in a layer of it. Or you might prefer butterscotch, or Nutella. Maybe you really hanker after peanut butter. Just think of these adaptable marshmallow bars as layers of goodness – start with the shortbread base, add in what you like, end with marshmallows. It’s a choose your own adventure in edible form!

preparation

Set rack in the middle of the oven, and heat oven to 350˚F. Line an 8×8 pan with parchment paper, leaving some flaps on each side. Set aside. Note: if you have an 8×8 square removable-bottom pan, this is the time to use it! Jan 2022: forget the 8×8 pan, use a quarter-sheet pan (it measures 9×13). The quarter-sheet is better, because it has helpfully low sides. Still use the parchment.

Cut marshmallows into thirds or halves (obviously, thicker pieces make a thicker marshmallow layer: please yourself in this) and reserve. Nope. Now just use mini-marshmallows, no cutting involved!

shortbread base

Using an electric mixer, beat the butter and sugar together until pale and fluffy. Stop the mixer, scrape down the bowl, then add in vanilla paste (or extract) and egg yolk. Beat again, until well mixed. Stop mixer again, add flour and salt, and beat on low speed until completely incorporated.

Scrape batter into prepared pan. With clean wet fingers (wet fingers keeps the dough from sticking to them) press the dough across the bottom of the pan. Work quickly; try to make the dough as even as you can.

Bake crust 20-24 min NOPE, 30-35 min for a larger pan, until golden brown around the edges but still puffy and soft in the center. Remove crust from the oven and let rest about 20 min.

Now you’ll need to move the crust out of the 8×8 pan and onto an ungreased, unlined cookie sheet. Use the flaps to carefully lift the crust out, then run a knife or spatula under the crust, and carefully slide it out onto the unlined baking sheet. Jan 2022: forget that noise! Leave the crust right where it is.

chocolate layer

If you will use chocolate, sprinkle the crust with some good quality chocolate chips, and return to the oven for 3-4 minutes. Remove from oven and spread the chocolate evenly and gently. A small offset spatula is the perfect tool for this. Let the crust rest about 10 more minutes.

Substitutes for chocolate in this layer: Nutella, butterscotch chips (melt as above), peanut butter, almond butter.

next layer: the jam

Add a layer of fruit preserves. I had some black raspberry jam to use. Apricot or raspberry or cherry would be great with chocolate – this is where your imagination comes in. At any rate, you’ll use 1/2 to 3/4 c of the preserves, and spread them thinly.

and top with marshmallow

Now arrange the marshmallows on top of the jam. Return the pan to the oven for 4-5 minutes, to soften the marshmallows. Remove from the oven, and turn the oven to use the broiler setting.

Use the back of a spoon (or your trusty offset spatula) to gently press and smoosh the top of each marshmallow. Once they are all slightly smashed, return the pan to the broiler. Watch the tops carefully! Toast the marshmallows to your desired shade; remember that they brown very quickly.

Remove the toasted cookie bars from the oven. You’re finally finished! Allow to rest at least 10 minutes, then lift the parchment right off the quarter-sheet pan onto a cutting board. To slice use a wet knife, wiping the blade with a wet cloth after each slice.

store in an airtight tin

The cookies will keep, well wrapped, at room temperature for up to 4 days. However, today, within three hours, the pan was mostly devoured by the three of us. You have been warned!

These endlessly adaptable marshmallow bars are even easier now, and they remain a favorite way to use up open jars of jam.