Preheat oven to 350 degrees F., rack in the middle position.
Bottom Layer:
½ cup butter (1 stick, 4 ounces, ¼ pound)
1-ounce square unsweetened chocolate (I used Baker’s)
½ cup white (granulated) sugar
1 cup all-purpose flour (pack it down in the cup when you measure it)
1 teaspoon baking powder
1 cup chopped nuts (I used pecans)
1 teaspoon vanilla extract
2 eggs lightly beaten (just whip them up in a glass with a fork)
Cream Cheese Layer:
8-ounce package cream cheese, softened (you’ll use 6 ounces for this layer and the remaining 2 ounces for the frosting)
¼ cup softened butter (½ stick, 2 ounces, 1/8 pound)
¼ cup white (granulated) sugar
2 Tablespoons all-purpose flour (that’s 1/8 cup)
½ teaspoon vanilla extract
1 beaten egg (just whip it up in a glass with a fork)
½ cup chopped nuts (I used pecans)
1 cup semisweet chocolate chips (I used Ghirardelli)
2 cups miniature marshmallows (I used Kraft’s Jet-Puffed)
Frosting:
¼ cup butter (½ stick, 2 ounces, 1/8 pound)
1-ounce square unsweetened chocolate (I used Baker’s)
reserved 2 ounces cream cheese
¼ cup milk
1 teaspoon vanilla extract
1-pound box powdered sugar
Place butter and unsweetened chocolate in saucepan over low heat. Heat just until chocolate melts. (You can do this in the microwave if you prefer.) Stir in sugar.
Combine the flour, baking powder, and nuts. Add them to the chocolate mixture. Stir well.
Stir in the vanilla and the eggs.
Spread the batter into a greased and floured 9-inch by 13-inch cake pan. (You can spray the inside with baking spray, if you’d rather.)
Make the cream cheese filling.
Start with the cream cheese. Cut off 2 ounces and reserve it for the frosting. (That’s one-quarter of the package.)
If your cream cheese isn’t soft enough to stir, heat it in a microwave-safe bowl for 10 to 20 seconds until you can stir it. If your next ingredient, the butter, is still cold, you can throw that in when you heat the cream cheese and do both together.
Combine the softened cream cheese with the butter, sugar, flour, and vanilla. Stir it until it’s smooth.
Add the beaten egg and stir until well combined.
Mix in the chopped nuts.
Spread the cream cheese layer over the chocolate layer. Use a rubber spatula to smooth it out.
Sprinkle the chocolate chips over the top. Do this as evenly as you can.
Bake at 350 degrees F. for 20 to 25 minutes. (Mine took 23 minutes.)
Take the pan out of the oven, sprinkle the top with the miniature marshmallows, and put it back in the oven to bake an additional 2 minutes.
While the marshmallows are baking, start your frosting. Your pan will come out of the oven before you’re through making the frosting, but that’s okay.
Melt the butter in a two-quart saucepan over medium-low heat. (You can also do this in a bowl in the microwave.)
Break (or cut with a knife) the unsweetened chocolate square into two parts and stir them into the butter.
Stir in the softened cream cheese and the milk.
Heat the mixture until it can be stirred smooth. (Again, you can do this in the microwave in 20-second increments, stopping to stir after each time period.)
Remove the saucepan from the heat (or the bowl from the microwave) and beat in the vanilla.
Beat in approximately a cup of the powdered sugar. When that’s incorporated, beat in another cup. When that’s incorporated, beat in the rest of the box. (Doing it this way keeps the powdered sugar in the bowl and not flying out like snow flurries all over your counter.) Stir the frosting until it’s smooth.
When the frosting is smooth, spread it over the hot Chocolate Marshmallow Cookie Bars, swirling it into the marshmallows. It’ll be soft, but don’t worry. It’ll firm up as the bars cool.
Set the pan on a cold burner or a wire rack to cool. When you can handle it without using potholders, slip the pan into the refrigerator and let it chill for at least an hour. (This makes the bars less crumbly and easier to cut.)
To serve, cut the bars into 32 pieces. (That’s 8 rows and 4 rows crisscrossing them.)
Hannah’s Note: Chocolate Marshmallow Bars are very rich. (Mike’s the only person I’ve ever known to eat four in one sitting.) Make sure you have a full carafe of strong coffee right next to the plate with the bars. You should also have another pot all ready to go in the kitchen.
Yield: One recipe makes 32 incredibly chocolaty marsh-mallowy bars.