Combine the strawberries, sugar, and water in a medium pan and bring the mixture to a simmer over medium-high heat, stirring often as the fruit softens. The berries should look collapsed and juicy, with the sugar fully dissolved into a bright red base.

Blend the cooked fruit right in the pan with an immersion blender, or mash it with a potato masher if you want a more textured sauce. The sauce should look mostly smooth, with no large firm pieces left behind.

Whisk the heavy cream and corn starch together in a small bowl, then stir that mixture into the strawberry puree and cook briefly until it thickens slightly. Look for a glossy, jam-like consistency that coats a spoon lightly instead of running like juice.

Transfer the sauce to a medium bowl and let it cool to room temperature before assembling the cake. If it still feels warm, wait longer, because warm sauce will soften the ice cream layers too quickly.

Set the ice cream out for 30 to 45 minutes before assembly so it softens enough to spread. It should feel like soft-serve when stirred, not fully melted or pourable.

Mix the crushed vanilla cookies and melted butter in a large bowl until all the crumbs are evenly coated. The texture should resemble damp sand that holds together when pressed in your hand.

Line the bottom of a 9 or 10 inch springform pan with parchment paper before adding anything else. The paper should sit flat with no big wrinkles so the frozen base releases cleanly later.

Press half of the cookie mixture into the bottom of the pan to form the first crust layer. Pack it firmly but gently so it holds together without turning dense and rock-hard in the freezer.

Spread half of the softened ice cream over the crumb base, then cover it with a thin layer of cooled strawberry sauce. The ice cream should glide into an even layer, and the sauce should stay in ribbons rather than sinking straight through.

Add the remaining crumb mixture, the rest of the ice cream, and a drizzle of strawberry sauce to finish the layers. Keep the top level and smooth so the cake freezes into neat, stackable slices.

Freeze the assembled cake on a flat shelf for 6 to 8 hours or overnight until completely firm. The center should feel solid when lightly pressed, and the layers should hold their shape when the ring comes off.

Let the cake stand at room temperature for 10 to 15 minutes before serving, and garnish with whipped cream and fresh strawberries if desired. The edges will soften slightly, which makes slicing much cleaner.