For the butterscotch sauce, put all ingredients in a pan. Bring to the boil, stirring regularly, then simmer for 2-3 minutes.
For the pineapple, using a cutter, remove the centre core of the pineapple rings. Pre heat the grill. Brush the pineapple rings with the oil and dust with icing sugar. Grill for 4-8 minutes until golden brown.
To serve, place the grilled pineapple down, fill the ring with a large scoop of ice cream. Drizzle some butterscotch sauce over the top and sprinkle with the chopped and roasted pecans.