Ingredients:
1 2/3 cups(215 grams) blanched almonds, toasted
1 2/3 cups(215 grams) blanched hazelnuts, toasted
3 tablespoons(50 grams) corn syrup
2 cups(400 grams) granulated sugar
Hot water, as needed for finishing
Directions:
Prepare your candy frame on a parchment lined baking sheet (see headnote), or draw a 12×12 in/30×30 cm square on a piece of parchment paper. Place the parchment paper—ink-side down—on a baking sheet. Lightly grease the parchment with nonstick spray. (Alternatively, you can also use lightly greased candy molds.) Also prepare a second baking sheet lined with parchment and greased with nonstick spray.
Bring a medium pot of water to a boil over high heat. Add the nuts, and return the water to a boil. Once the water is boiling again, remove the pot from the heat and cover with a tight-fitting lid. Soak the nuts for 5 minutes, then drain well.
Transfer the nuts to the bowl of a food processor and grind until coarsely chopped. Then, transfer to a medium heat-safe bowl. Set aside.
Lightly grease a baking sheet with a thin coating of nonstick spray. Don’t worry about cleaning the food processor bowl—you will use it again.
In a medium pot, layer the corn syrup, granulated sugar, and 1/2 cup (115 grams) water (in that order). Stir the mixture with the probe of your digital thermometer (or the handle of a wooden spoon) to break up any dry pockets or clumps of granulated sugar—but the goal is to only stir enough to evenly combine the ingredients, and no more.
Cook the mixture over medium heat until it registers 240°F/115°C on a thermometer.
Pour the hot sugar over the ground nuts in the bowl and stir a few times to combine with a silicone spatula. Pour the mixture onto the prepared greased baking sheet, and cool to room temperature.
Transfer the mixture to the food processor, working in 2 to 3 batches as necessary. Grind the mixture until very smooth. If the mixture becomes oily or appears separated, drizzle in a small amount (about 1 tablespoon / 15 grams) of hot water and continue to process until the mixture comes back together.
Scoop the mixture into the center of the prepared frame, and spread/press into an even layer (about ½-inch/1 cm thick). If using greased candy molds, press the marzipan firmly into the molds. Let set for 2 hours before cutting or unmolding.
Cut into squares (about 1 in/2 ½ cm) with a sharp knife, or unmold the set marzipan. If desired, dip the squares of marzipan in the tempered chocolate to coat, or wrap each piece individually in cellophane or wax paper. Store in an airtight container for up to 3 months.