Line a baking sheet with parchment paper.

In a medium saucepan, mix the granulated sugar, light corn syrup, and water. Heat over medium until the sugar dissolves.

Bring the mixture to a boil without stirring until it reaches the soft ball stage (240°F).

While the sugar mixture is cooking, whip the egg whites until they form stiff peaks.

Carefully pour the hot sugar mixture into the whipped egg whites while mixing continuously.

Stir in the vanilla extract, chopped nuts, and mini marshmallows.

Pour the nougat mixture onto the prepared baking sheet and spread it evenly.

Allow it to cool at room temperature until set.

Once cooled, use a sharp knife to cut the nougat into squares or rectangles.