Use a loaf tin or other suitable container (I lined mine with clingfilm because originally I wanted to make ice cream sandwiches – you don't need to line it unless you want to turn the ice cream out).
Whip the double cream until you have stiff peaks. It will whip better if both the cream and the bowl are cold.
Pour the condensed milk over the whipped cream and use a spatula to fold together.
Add the vanilla paste and stir it in gently.
Add half the chocolate shavings and fold them into the cream.
Pour half of the cream into your container then sprinkle with half of the reserved chocolate shavings. Pour the rest of the cream and add the remaining chocolate shavings on top.
Cover with clingfilm and freeze for at least 5 hours or overnight.
To make the chocolate sauce, put all the ingredients into a small saucepan and whisk together over low heat until you have a sauce. Strain through a sieve into a jug. Keep warm.
Take the ice cream out of the freezer for at least 15 minutes to soften. Dip a spoon or an ice cream scoop into a glass of hot water then scoop the ice cream into bowls or cones to serve.
Drizzle with the chocolate sauce and dig in!