Roughly crush the digestive biscuits in a bowl. Stir in the flaked almonds and the melted butter. Melt the chocolate in a large bowl over a saucepan of simmering water, then stir in the condensed milk. Pour this chocolate mixture over the biscuits along with the Baileys and stir well to combine all the ingredients. Line a 2lb loaf tin with Clingfilm (or baking parchment) and spoon the mixture into it. Place the tin in the fridge to set for at least 2 hours.
For the butterscotch sauce, heat the sugar and water in a heavy based saucepan until the sugar dissolves, then stir mixture once and leave over a medium heat until the syrup turns golden. Add the cream and the butter and then whisk until all the ingredients are combined and melted. Remove from the heat and leave to cool completely.
To make the ice cream, pour the milk and cream into a pot and bring it to just under the boil. Whisk the egg yolks and sugar until pale and thick. Pour the hot cream and milk mix over them, whisking all the time. Sieve this mixture back into the pot and cook on a low heat until the mixture coats the back of a spoon, stir constantly. Remove from the heat and leave to cool for a few minutes, and then churn in an ice cream machine until thick. Pour the ice cream into a freezer container and drizzle the butterscotch sauce over it, and keep in the freezer.
Serve a slice of the cake with a scoop of ice cream.