In a chilled mixing bowl, pour in the cold heavy whipping cream and add powdered sugar. Beat on medium-high speed for 3 to 5 minutes until soft peaks form.

In a separate mixing bowl, combine the mascarpone cheese with fresh lemon juice and lemon zest. Mix until smooth.

Gently fold the whipped cream mixture into the mascarpone until fully incorporated.

Layer crushed butter cookies or graham cracker crumbs at the bottom of serving cups.

Spoon in a layer of the lemon mascarpone mousse over the cookie base, filling halfway.

Repeat layering cookies and mousse until cups are filled, finishing with mousse on top.

Cover the cups and refrigerate for at least 1 hour to allow the mousse to set.

Garnish each cup with fresh berries before serving.