First roast the pecans or almonds. Preheat oven to 175° C and place the nuts in a single layer on a baking sheet. Bake for about 5 to 10 minutes stirring the nuts once or twice during the baking. Pay attention as nuts get burnt very quickly. You can also do this in a cast iron pan over stove top keeping the heat low and stirring frequently. Cool and chop the nuts coarsely.
In a small bowl, dissolve the coffee in two tbsp hot water or milk & set aside to cool. You probably won't use all of it.
Using a stand or hand mixer, whip the double cream until stiff peaks form. Gently fold in the condensed milk, vanilla, salt, the liqueur & most of the nuts, saving 3-4 tbsp for garnish.
Add the coffee a teaspoon at a time, tasting until the mixture is to your taste.
Transfer the mixture to a freezer-proof container, sprinkle the remainder of pecan nuts on top & freeze for at least 8 hours or overnight.