Add the cold water and gelatin into a small mixing bowl and mix using a fork until well combined. Set aside to rest.
Next, add the boiling water and sugar into a saucepan. Use a whisk to mix for 3 minutes until the sugar is dissolved.
Add the gelatin and whisk gently until the gelatin is dissolved.
Set the mixture aside to cool to room temperature for about30 minutes.
Add the cooled mixture to the bowl of a stand mixer and fit it with the whisk tool. Whisk on high speed for 10-12 minutes until the mixture triples in volume and resembles a thick glossy meringue. Add the vanilla extract, strawberry flavouring and pink food gel at about the 5-minute mark.
Add the marshmallow mixture on top of the cookie dough and spread using a small spatula. Sprinkle with sprinkles. Place in the fridge to set overnight.
Slice up using a large knife brushed with oil. Serve.