Step 1: Make the Strawberry Sauce

1. Combine frozen strawberries, sugar, and water in a medium saucepan over medium-high heat. Stir frequently until the berries soften and release their juices (about 10 minutes).
2. Puree the mixture with an immersion blender for a smooth sauce or mash with a potato masher for a chunkier texture.
3. Whisk together heavy cream and cornstarch in a small bowl until smooth, then stir into the strawberry mixture. Cook until slightly thickened (3–5 minutes). Let cool completely.

Step 2: Prepare the Cookie Crust

1. Mix crushed vanilla cookies with melted butter in a large bowl until evenly coated. Reserve about half a cup for topping.
2. Line the bottom of a 9-inch springform pan with parchment paper and press half of the cookie mixture firmly into the base to form an even crust.

Step 3: Assemble the Cake

1. Let the ice cream soften at room temperature for about 30–45 minutes before assembly. Spread half of the softened ice cream over the cookie crust in an even layer and freeze for at least one hour.
2. Spread a thin layer of cooled strawberry sauce over the ice cream layer, followed by another layer of cookie crumbs. Repeat with the remaining ice cream and drizzle more strawberry sauce on top.

Step 4: Freeze and Serve

1. Freeze the assembled cake for at least 6–8 hours or overnight to set completely. Remove from freezer about 10–15 minutes before serving to make slicing easier.
2. Garnish with whipped cream and fresh strawberries as desired.