Start by lining a 7-inch springform pan with parchment paper, ensuring it sits flat against the base. Trim the edges of the ladyfingers if necessary for a neat fit.

Arrange the ladyfingers upright along the sides of the pan, pressing gently to secure them. Briefly dip additional ladyfingers in strawberry juice or simple syrup, then lay them at the bottom of the pan to form a solid base.

Blend fresh strawberries, sugar, and lemon juice in a food processor until smooth. Transfer this puree to a small saucepan and gently warm it over low heat.

Soak the gelatin in cold water for about 5 minutes until it blooms. Gradually stir the bloomed gelatin into the warm strawberry puree until fully dissolved.

In a mixing bowl, combine the mascarpone and vanilla extract, whisking until smooth. In a separate bowl, whip the cold heavy cream to soft peaks. Gently fold the whipped cream into the mascarpone mixture, then add the cooled strawberry mixture.

Spread half of the strawberry mousse evenly into the prepared pan. Scatter a layer of chopped strawberries over the mousse, followed by another layer of dipped ladyfingers. Add more strawberries, then use the remaining mousse to cover the top.

Cover the pan with plastic wrap and refrigerate the cake for a minimum of 6 hours; overnight chilling is ideal.

Once chilled, remove the springform ring and peel away the parchment paper. Decorate the top with fresh strawberries and whipped cream.