In a medium saucepan, combine granulated sugar, light corn syrup, water, and salt. Place the saucepan over medium heat, stirring until the sugar dissolves.

Allow the mixture to come to a boil without stirring. Use a candy thermometer to monitor the temperature. The target temperature is 240°F (115°C).

While the sugar mixture is boiling, beat the egg whites in a clean, dry bowl until stiff peaks form.

Once the sugar mixture reaches the desired temperature, remove it from heat.

Gradually pour the hot sugar syrup into the beaten egg whites, whisking continuously. Be cautious to avoid pouring the syrup onto the beaters to prevent splattering.

Continue to beat the mixture at high speed until it cools down and forms a glossy marshmallow sauce. This process may take about 5-7 minutes.

Add vanilla extract and beat for an additional minute to incorporate the flavor.

Transfer the homemade marshmallow sauce to a jar or airtight container. Allow it to cool completely before sealing.

Store the marshmallow sauce in the refrigerator for up to two weeks. Serve it as a delightful topping for desserts, beverages, or enjoy it as a sweet spread.

Relish in the satisfaction of creating your own Homemade Marshmallow Sauce, adding a delightful touch of sweetness to your culinary creations.