DIY Sandwich Cookies Better than Any You’ll Find at the Grocery Store

By Dennis Prescott |

© Dennis Prescott

There are times in life when you just need to take your cookie game to the next level. Now is the time to set aside your tried-and-true chocolate chip recipe and go with something new.

I love marshmallows, and I love cookies. Together, they make one heck of a sandwich.

Oatmeal–Chocolate Chip & Grand Marnier–Marshmallow Cookies


  • ¼ cup confectioners’ sugar
  • ¼ cup cornstarch
  • Sunflower oil, for greasing
  • ¾ cup warm water
  • 1 Tbsp. instant espresso
  • 3 envelopes unflavored gelatin
  • 1 cup sugar
  • 1 cup corn syrup
  • 2 tsp. vanilla extract
  • 2 Tbsp. Grand Marnier

Oatmeal–Chocolate Chip Cookies

  • 1 stick butter (½ cup), at room temperature
  • ½ cup sugar
  • ½ cup brown sugar
  • 1 egg
  • 2 tsp. vanilla extract
  • 1¼ cups flour
  • 1 tsp. baking powder
  • ¼ tsp. salt
  • ¾ cup rolled oats
  • 1 cup milk chocolate chips


  • 8 oz. semisweet chocolate, coarsely chopped
  • 1 cup heavy cream
  • 1 Tbsp. unsalted butter, at room temperature


Sift together the confectioners’ sugar and cornstarch into a bowl. Lightly grease an 11-inch-by-9-inch pan with sunflower oil and dust with about 2 tablespoons of the sugar and cornstarch mixture. Set aside.

In the bowl of a stand mixer, combine ½ cup of the warm water with the instant espresso and whisk until the coffee dissolves. Add the gelatin to the coffee mixture and whisk to combine.

In a saucepan with a candy thermometer attached, combine the sugar, corn syrup, salt and the remaining ¼ cup of water, and heat on medium stirring until the sugar dissolves. Bring to a boil, and cook until the thermometer reaches 240°.

With a stand mixer fitted with the whisk attachment, beat the gelatin mixture on low, while carefully adding the boiling liquid. Turn the mixer to high, and whisk for 8 to 10 minutes until the mixture is doubled in volume, with stiff peaks. Add the vanilla extract and Grand Marnier and whisk for an additional minute.

Pour into the prepared pan, and smooth the mixture with a spatula as best you can. Dust the top with the remaining sugar mixture and cover with plastic wrap. Set aside for at least 2 hours, or overnight.


Preheat the oven to 375°. Line a baking sheet with parchment paper.

In the bowl of a stand mixer, combine the butter and sugars and beat until smooth. Add the egg and the vanilla, and beat for another minute to combine. Sift in the flour, baking powder and salt, add the oats, and beat until combined. Fold in the chocolate chips.

Roll the dough into 1-inch balls, and arrange on the prepared baking sheet at least 2 inches apart. Chill the tray in the freezer for 10 minutes.

Bake the cookies for 10 to 12 minutes, then cool on a rack for 20 minutes.


Place the chocolate in a medium heat-proof bowl, and set it aside.

In a small saucepan, bring the cream to a simmer, and pour it over the chocolate. Allow the chocolate to melt (about 3 minutes), then add the butter and whisk to combine.

To assemble

Cut the set marshmallows into rounds the same size as the cookies, about 2 inches. Make sandwiches with 2 cookies and 1 piece of marshmallow, and dip one half of each sandwich into the chocolate ganache. Place on a rack and allow the chocolate to set for about 20 minutes. Enjoy.

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