Nest a 7-inch springform pan inside a 9-inch springform pan.

Using a serrated knife, gently saw one rounded tip off the enough ladyfingers to fit around the inside of the 9-inch springform pan. Slide the ladyfingers between the two springform pans, creating a circle around the inside of the 9-inch springform pan.

Lifting the 7-inch springform pan slightly, slide ladyfingers across the bottom of the 9-inch springform pan in an even layer. Carefully lift the 7-inch springform pan out. Fill in any empty areas with pieces of ladyfingers.

In a small saucepan, pour the water. Sprinkle the gelatin over the top and allow it to rest for 3 minutes. Transfer the saucepan to the stovetop and cook over low heat, stirring constantly, for about 1 minute or until the gelatin has dissolved. Add the remaining sugar and cook while stirring until the sugar has dissolved completely. Remove the saucepan from the heat and bring to room temperature.

In a food processor or blender, place the 1 pound of strawberries and ⅓ cup sugar. Pulse or blend until the strawberries are pureed. Set aside.

In a cold mixing bowl, pour the heavy cream. Whip on medium-high speed to form soft peaks. Remove about 1 ½ cup of the whipped cream, cover, and refrigerate.

To the remaining whipped cream with the mixer running, add the room temperature gelatin in a steady stream. Continue beating the heavy cream until stiff peaks form.

To the whipped cream, fold in the strawberry puree and remaining sliced strawberries.

Spoon the strawberry mousse into the 9-inch springform pan being careful not to disturb the ladyfingers. Smooth evenly. Loosely cover with plastic wrap and refrigerate overnight.

Prior to serving, spread the refrigerated whipped topping over the top of the strawberry mousse and garnish with halved strawberries.