Combine the thick cream (50 cl) and powdered sugar (75 g) in a saucepan. Add 1 open and scraped vanilla pod, bring to a boil, then cover and infuse off the heat for 10-15 minutes.
Pour into 4 verrines and refrigerate for at least 6 hours to set.
Trim and chop the Gariguette strawberries, place in a bowl, sprinkle with 60 g powdered sugar, gently stir, and marinate, stirring occasionally.
Crush the speculoos biscuits into crumbs.
Whip the whipping cream (25 cl) with the remaining powdered sugar until stiff peaks form. Transfer to a piping bag.
Divide the marinated strawberries over the set panna cotta in each verrine. Sprinkle with some speculoos crumbs.
Pipe whipped cream over the strawberries and finish with the remaining speculoos crumbs for a delightful crunch.
