Does it still count as a present if you can see inside the box? I'm going to say yes.
In a big bowl, whip the heavy cream together with the espresso powder.
Add the sugar to the bowl until stiff peaks form.
Cover the bowl and leave it in the fridge so the peaks can stiffen.
Now to make the box proper. Using the melted dark and white chocolate, “glue” the chocolate squares together. Don't put the top piece on just yet, though you can decorate the top if you like. Make sure the chocolate is set before moving on.
Scoop the espresso cream you chilled into the box, top that with some whipped cream, and gently push the strawberry in so it doesn't all gush out. Finally, place the top chocolate square into the cream.