Add pecan halves to food processor to chop the nuts. Pulse a few times to get a variety of sizes.
Add chopped nuts to a saucepan with 4 tablespoons of butter and a quarter cup of sugar. Place over medium heat and stir continuously until butter and sugar form a crust around the nuts. Set aside the nuts to cool.
Add sugar and salt to a mixing bowl and whisk to combine. In a large mixing bowl mix the heavy cream with the sugar and salt mix and beat on high using a hand mixer until soft peaks form. Do not over whisk cream.
Add the vanilla extract (or rum extract). Add the buttered pecans. Fold ingredients together.
Place cream mixture into a loaf pan and freeze for 6-8 or overnight. Sprinkle some chopped nuts to decorate.