In a 180°c/360°F oven for roughly 15 minutes - you want the flour to be slightly darker and to smell a little biscuity - this both kills potential bacteria and adds flavour to the cookie dough.
In a bowl whisk the soft butter with the sugars until the mixture lightens a little and is a bit fluffier. Add salt and vanilla essence and beat in flour with a spoon to make a rough dough. This may still be a little warm so set in the fridge for half an hour or so to chill, then mix in the chocolate chips.
Take a good handful for each bowl and press into around 5 small bowls - these should either be greased or covered in two layers of clingfilm to make sure you can get the cookie "shell" out after freezing!
Get the ice-cream and fill the cookie bowls to the top then smooth out with a spoon to level the surface. Freeze these until the ice cream is hard again, then ease out of the bowls onto a rack, bowl side up.
Make your magic shell chocolate sauce - heat the chocolate in 30 second bursts in the microwave, stirring after each until it's all molten and glossy. Pour the sauce over the cookie domes and watch it harden.