I made this S'mores Tart for Valentine's Day because I was in the mood for something chocolatey and fun, but not overly complicated. It starts with a simple graham cracker crust. You bake the crust then add a creamy chocolate filling. The finish is a billowy marshmallow topping which you "toast" by putting under the broiler or torching.
9-Inch Tart Pan
You'll need a 9-inch removable bottom tart pan to start. If you don't have one, a 9-inch round cake pan lined with foil should work. The graham cracker layer is baked and holds together well, while the chocolate layer is cooked on the stove and thickens quickly. One you have those two components, you can make the topping immediately or set it aside and make the topping later.
I topped mine while the chocolate filling was still slightly warm (not hot). I just let it cool for a few minutes, added the marshmallow, broiled, then cooled the tart at room temperature before chilling. Slices were served cold.
Billowy Marshmallow Topping
I've been using the double boiler method a lot lately and felt very comfortable making this topping. It starts by whisking the egg whites, sugar, and cream of tartar in the stand mixer bowl over simmering water, then finishing it off by whipping everything with the stand mixer's whisk attachment.
If you don't have a stand mixer, you could probably do the whole thing with a handheld mixer, but it's much easier (and less noisy!) to let the stand mixer do the whipping once the sugar is dissolved.
Once assembled, you can use a torch or put the whole tart under a broiler. The S'mores Chocolate Tart fit perfectly in my Breville Smart Oven, so I used the broil setting on that. I used "high" and it darkened pretty quickly. Since I wasn't trying to cook the inside, the high setting was the way to go.
After broiling, the tart will still be warm, so it needs a little time to cool before you chill it thoroughly. Another option is to just make the crust and filling first, then make the topping and torch before serving.
Making Ahead and Storing
I made my tart in one day and served it in the evening. After a full night in the refrigerator, the crust was still pretty firm and the tart sliced neatly. That being said, the longer these kinds of tart sit the softer everything will become. If you want to make it a day ahead, I suggest making just the crust and filling, freezing, then making the marshmallow topping on serving day. I personally will freeze the rest of mine because we are serving it to ourselves and don't mind if the marshmallows topping gets a little weepy in the freezer.
An Interesting Thing About Cornstarch
It turns out cornstarch is one of those ingredients that can vary in density, which surprised me. I was looking at the label on my usual Argo and then the Clabber Girl cornstarch my husband picked up. Argo says 1 tablespoon weighs 8 grams while Clabber Girl says 10 grams. That's a big difference for something so basic! It could have to do with how the starch is ground and how tightly it packs into a spoon, but it also means that depending on what brand you use, you might end up with a filling that's a tiny bit thicker or softer.
This recipe only uses 2 tablespoons, so it's not a huge deal here, but in a recipe that calls for something like ⅓ cup of cornstarch, the weight could vary quite a bit -- roughly 43 grams versus 53 grams. That's a full tablespoon difference. For that reason, I'm going to keep including weights next to cornstarch measurements whenever I can.
Recipe
S'mores Tart
Ingredients
- 1 ½ cups graham cracker crumbs
- ¼ cup sugar (50 grams)
- ⅓ cup salted butter (75 grams)
Chocolate Filling
- ½ cup sugar plus 1 tablespoon (112 grams)
- ⅛ teaspoon salt
- 2 tablespoons cornstarch (15 grams)
- 2 cups minus 2 tablespoons whole milk (15 oz)
- 3 large egg yolks
- 1 ½ tablespoons butter (20 grams)
- 2 ounces unsweetened chocolate, chopped (56 grams)
- 1 teaspoon vanilla extract
Meringue Topping
- 5 large egg whites
- ¼ teaspoon cream of tartar
- 1 cup sugar (200 grams)
- ½ teaspoon vanilla extract
Instructions
- Preheat oven to 350 degrees F. Have ready an ungreased 9-inch removable bottom tart pan.
- In a large bowl, mix together the graham crackers crumbs and sugar. Add melted butter and stir until evenly mixed, then press as tightly as you can into bottom and up the sides of the tart pan.
- Set the tart pan on a baking sheet and bake at 350F for 10 minutes. Let cool.
- Combine the sugar, salt and cornstarch in a medium size saucepan. Whisk in the cold milk. In a separate bowl, whisk together the egg yolks.
- Heat the milk mixture just until hot and steamy, then gradually whisk it into the egg yolks to temper. Add egg mixture back to the saucepan and whisk constantly until thickened and smooth and big bubbles break the surface. Whisk in the butter until melted, then remove from heat and stir in the chocolate. Lastly, stir in the vanilla.
- Scrape the filling into the crust and cover with a piece of greased plastic wrap while you make the topping. You can make it right away or leave the filling to cool and come back and do it later.
Marshmallow Topping
- Put the egg whites, sugar, and cream of tartar in the bowl of a stand mixer. Set the bowl over a saucepan of gently simmering water (double-boiler style), making sure the bottom of the bowl doesn't touch the water.
- Whisk vigorously while holding the bowl steady with an oven mitt until the sugar is completely dissolved and the mixture feels smooth (not grainy) between your fingers. This should take about 5 minutes, and an instant thermometer should read 160°F.
- Transfer the bowl to the stand mixer fitted with the whisk attachment. Beat on high speed for about 5 minutes, or until the meringue is billowy, glossy, and holds stiff peaks. Towards the end of the beating time, add the vanilla.
- Spread the meringue over the cooled tart, then place it under the broiler for 30-60 seconds, watching constantly, just until the top is lightly toasted. Remove immediately since meringue can go from golden to burnt very quickly.
- Let the tart cool at room temperature, then chill for 3 hours or until cold. Remove from pan (or serve out of the pan if you wish) and cut into slices. Store in the refrigerator.
Method 2 -- Torch
- Another way to do this would be to prepare the crust and filling earlier, chill, add marshmallow topping and torch the crust. That method gives you a variety of temperatures because you'll have the cold crust and filling and the warm topping. I chose to just do everything ahead of time and serve the whole tart cold.
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