Grease & line a baking sheet with parchment paper

Lay out the pecan halves on the prepared sheet. Put the sheet of pecans next to, or actually on, the stove-top

In a large, heavy-bottomed saucepan (a cast iron skillet would be ideal) over a medium heat, add the butter sugar and water. Stir to until the butter is melted and the sugar has dissolved

Turn the heat up to high and allow the mixture to bubble and begin to evaporate. Do not stir during this stage

Keep a close eye and nose on the bubbling mixture, you're looking for the colour to start turning brown to begin smelling like caramel. It can get to this stage and suddenly go over in an instant and begin to burn. Just as you think the mixture is at this point, pour it carefully over the pecans. Be very careful, the mixture is exceedingly hot and sticky

Allow to cool completely

Break up into fairly large shards. Set aside 6 of these shards and put the rest of the pecan toffee into a large mixing bowl

Using a large pestle (or the end of a rolling pin, like I did) grind the toffee into smaller pieces - not quite a powder, you want small chunks

Set aside while you make the ice cream

In a large saucepan over a very low heat add the milk and sugar, stirring to dissolve the sugar. Set aside and allow to cool completely

Stir in the cream and the vanilla paste/extract

Pour the mixture into your ice cream machine and churn following the manufacturer's instructions

A couple of minutes before the end of the churning process, with the machine still turning, spoon in the ground pecan toffee

When the toffee has been combined well into the ice cream, turn the mixture out into a 1-litre lidded tub and put into the freezer to 'ripen' for at least a couple of hours