Homemade Mallomar Bars

Ingredients

• For the base:
• 10 ounces crushed graham cracker crumbs
• 1 1/2 sticks unsalted butter, melted
• For the marshmallow layer:
• 4 teaspoons gelatin
• 1/2 cup water, divided
• 1/2 cup light corn syrup, divided
• 1 cup plus 2 tablespoons granulated sugar
• 1 teaspoon pure vanilla extract
• For the chocolate topping:
• 4 ounces bittersweet chocolate, finely chopped
• 1/2 cup heavy cream

Directions

1. In a large bowl, mix the graham crumbs with the butter until the butter is worked through and the crumbs are damp all over. Pack the mixture firmly across the bottom of a 9- by 13-inch pan, then leave it aside.
2. Pour 1/4 cup water into a small bowl, scatter the gelatin across the surface, and give it at least 5 minutes to bloom. Add 1/4 cup corn syrup to the bowl of a stand mixer. In a medium saucepan set over medium-high heat, combine the remaining 1/4 cup corn syrup, remaining 1/4 cup water, and the sugar and stir just until the sugar has dissolved. Let it boil without more stirring until an instant read thermometer shows 240°F.
3. Right away, transfer the hot syrup to the mixer bowl, then add the softened gelatin and vanilla. Beat on medium speed until everything comes together, about 1 minute. Raise the mixer to medium high and continue beating until the marshmallow turns pale and airy, about 8 minutes.
4. Spread the marshmallow onto the graham cracker base, using an offset spatula to even out the surface. Refrigerate until the layer holds its shape, about 30 minutes.
5. Put the chocolate in a medium bowl. Warm the cream in a small saucepan until it simmers, then pour it over the chocolate and whisk until the mixture is glossy and smooth.
6. Pour the chocolate layer over the marshmallow and chill until the topping has set, about 15 minutes. For 24 squares, slice the pan into 4 vertical rows and 6 horizontal rows.