How do you make the shell for this dinosaur egg dessert?

This seems to be a version of the chocolate ball, only not intended for melting.

The standard chocolate ball is made by covering the inside of a spherical mold with tempered chocolate, then melting away the bottom so it can be placed over a scoop of ice cream. For the detailed process, see this video.

This version seems to use white chocolate instead. It is impossible to tell what the dots are, exactly, my best guess would be Oreo cookies ground to fine crumbles. An alternative would be ground (unpeeled) nuts like hazelnuts, or some poppy seed (that's probably not what the picture uses, but it would work well when you recreate the recipe).

The biggest problem would be the mold, I have no idea where you can source one. There are methods for making your own silicone molds from mixing caulking silicone with cornstarch, but I wouldn't consider them foodsafe. Maybe you can get away with using the paint-a-balloon method, but the shape won't be completely egglike. You may be able to hide this by using a more egg-shaped balloon, like the ones with a bit of a tube before the round body, and melting some more of the base away (where the balloon's tube is).

The egg in the picture looks like the ice cream is larger than the base. For that, you may need to work in two halves and glue them, which would be very fuddly work.

The nest looks simple, just use whatever form of chocolate sprinkles and shaved chocolate you have.

The eggshell is white chocolate with what looks like crushed cookie mixed in it to give the black speckles. The melted white chocolate mix is the poured into 2 molds (probably silicone) to give it that shape. Once cooled the two halves of the egg are joined together using a food glue or melting the edges of the egg halves and pressing them together.

It's served up on a bed of shaved chocolate in that picture but you could use crushed cookies, whole cookies, or anything edible that gives that effect.