Instructions:

• Step 1: Prepare the Gelatin - In a small bowl, combine 1/3 cup of cold water with the unflavored gelatin and instant espresso powder. Let it sit for about 10 minutes to allow the gelatin to bloom and the espresso to dissolve.
• Step 2: Cook the Sugar Mixture - In a medium saucepan, combine the granulated sugar, corn syrup, remaining 1/4 cup of cold water, and a pinch of salt. Cook over medium heat, stirring until the sugar dissolves. Once it begins to boil, stop stirring and allow it to reach a temperature of 240°F (115°C) on a candy thermometer.
• Step 3: Combine and Whip - Once the sugar mixture reaches the correct temperature, remove it from heat. With the mixer running on low speed, carefully pour the hot sugar mixture into the bloomed gelatin. Gradually increase the speed to high and beat for about 10 minutes until the mixture becomes thick, glossy, and forms stiff peaks. Add the vanilla extract during the last minute of mixing.
• Step 4: Set the Mixture - Pour the marshmallow mixture into the prepared baking dish, using a spatula to spread it evenly. Dust the top with powdered sugar to prevent sticking. Let it sit at room temperature for at least 4 hours or overnight to set.
• Step 5: Cut and Dust - Once set, use a sharp knife or pizza cutter dusted with powdered sugar to cut the marshmallows into squares. Toss each piece in powdered sugar to coat all sides.