Mix the cookie crumbs and melted butter. Press firmly into a 20 cm (8″) springform pan or mousse ring. Chill while prepping the mousse.

Soften gelatin in 40 ml cold water for ~5 min. Microwave briefly (5 s) or warm gently until fully melted—avoid boiling.

Whisk cream, milk, sugar, and vanilla extract until sugar dissolves. Stir in the warm gelatin mixture until incorporated. Cool slightly, then pour over chilled crust. Chill in the fridge for at least 4 hours or overnight.

In a small pot, combine strawberries, sugar, and lemon juice. Cook on medium heat, stirring gently, until berries begin to release juices (~5–7 min). Remove from heat and stir in liqueur if using. Cool completely.

Macerate strawberries with sugar and lemon juice for 15–20 min, then mash lightly. Whisk in cream and milk until sugar dissolves. Chill mixture thoroughly, then churn in an ice-cream maker per instructions (or freeze in a container, stirring every 30 min to avoid iciness). Store frozen until ready to serve.

Toss strawberries with sugar and lemon juice. Let sit for 30 min to release juices—perfect topping for mousse and ice cream.

Remove mousse cake from pan and place on a serving plate. Add a generous spoonful of strawberry compote on top or beside the cake. Scoop strawberry ice cream onto the plate. Arrange macerated strawberries near the cake. Garnish with optional mint or basil leaves, a light dusting of powdered sugar, or a drizzle of melted dark chocolate for visual appeal.