When we were little, we used to go to Nantucket to stay with my grandparents in the summer. I remember some details so vividly: the smell of the salt water, the tangle of low blueberry bushes edging the sandy driveway, the sticky feeling on my fingers after eating bags of penny candy from the fudge shop.
On bright Nantucket mornings, we'd pack up for a day of swimming. That, too, I remember in flashes: the hot beach, the sand baked under the midday sun. My bare feet would burn as we'd walk to stake out a spot and settle down, beach chairs and towels and plastic buckets and all. Then my sisters (and cousins and parents and aunts and uncles and whatever family friends were there that week, too) and I would energetically and enthusiastically throw ourselves into the business of beach-going: swimming and building sand castles and boogie-boarding.
All that activity works up an appetite. My grandmother would pack us sandwiches, and we'd clamor for ours, unwrapping them quickly. There were only two options, no switching it up: bologna and mayo on squishy white bread or peanut butter and marshmallow Fluff on squishy white bread. See the theme?
Never again have I eaten as much Fluff as I did in those summers, and the taste of it takes me back to those beaches. In the years since, I've bought it a few times out of a nostalgia, and always marveled at how good it tastes (sorry, sorry, I know it's not trendy or remotely good for you and totally processed but it IS DELICIOUS).
The closest I've gotten to that taste since is by making homemade 7-minute frosting, a billowy confection of egg whites and sugar that makes a fantastic alternative to buttercream for cakes since it’s lighter and not so rich. But that frosting is still not quite Fluff-like: it’s too sweet to really replicate that distinctive marshmallow flavor; the sugar masks the hint of vanilla...or maybe it’s not vanilla but some elusive bakery-sheet-cake imitation flavoring. But whatever it is it’s good! So I've just caved, and decided it's better to embrace the Fluff entirely and in the scheme of how often I make everything from scratch, I’m okay with it.
And I loved that peanut butter and Fluff combination so much that I'm bringing it back!
Starting with a chewy double chocolate cookie, these look like a classic sandwich cookie but they aren’t, thanks to the filling. Of course you could certainly use a simple buttercream for the filling if you want a straightforward Oreo-style cookie. But my filling is, I must say, quite excellent and unusual. I fold marshmallow Fluff (YUP, here's your reason to buy it!) into my buttercream, and then I add some peanut butter too. The result is a subtly nutty and not-too-sweet flavor that is, frankly, addictive. It would be very good if you save some of the filling and warm it slightly and eat it over ice cream. Not into peanut butter? (Who are you? Sorry. That was rude.) Try tahini or almond butter! Or leave it out and go full-on marshmallow flavor.
A note on the cookies: I use half semisweet chocolate chips and half chopped dark chocolate but you can use all dark or all semisweet. You can also use all chips or all chopped, I just like the blend of textures as some of the chopped chocolate shards melt slightly and some of the chips stay intact. Sometimes I add cacao nibs for crunch and that’s totally optional, as is the espresso powder which helps amplify the chocolate flavor of these chewy cookies. Don’t overbake them! The chewiness is one of the best parts.
Chocolate Peanut Butter Marshmallow Sandwich Cookies
For the filling
8 tablespoons (1 stick) unsalted butter, at room temperature
2-4 tablespoons milk
2 cups marshmallow fluff
1 cup confectioners' sugar
1/4 teaspoon salt
1 teaspoon vanilla bean paste
1/2 cup creamy peanut butter (optional)
For the cookies
18 tablespoons (2 sticks + 2 tablespoons) unsalted butter, at room temperature
1 3/4 cups granulated sugar
2 large eggs
1 1/2 teaspoons vanilla extract
1/8 teaspoon espresso powder (optional, for more chocolate-y flavor)
2 cups (8 1/2 ounces) all-purpose flour
3/4 cup cocoa powder
1 teaspoon baking soda
1/2 teaspoon salt
3/4 cup semisweet chocolate chips
3/4 cup chopped dark chocolate
1/2 cup cacao nibs (optional)
Preheat the oven to 350° F.
To make the cookies: Cream together the butter and sugar until pale and fluffy. Add the eggs, one at a time, and then the vanilla, beating between each addition until smooth.
In a separate bowl, whisk together the espresso powder(if using), flour, cocoa, baking soda, and salt. Add the dry ingredients to your butter/sugar mixture and beat until the dough just comes together. Don't overmix!
Fold in the chocolate chips and chopped chocolate and cacao nibs (if using).
Scoop the dough onto a parchment-lined baking sheet, leaving a few inches between each and press down on each one slightly to flatten.
Bake for 8-10 minutes, or until the top and sides are just set. Don't overbake or they won't be nice and chewy! Let cool for 10 minutes then transfer to a wire rack to finish cooling completely.
While the cookies cool, make the filling: Beat together all the ingredients until you have a smooth and fluffy consistency. Start with the lesser amount of milk and add more as needed.