Prepare a large bowl or pan of ice water.

In a small skillet, melt the butter over medium heat. Add the nuts, and sprinkle with the 2 tablespoons sugar. Cook, stirring continuously, until the nuts are toasted and caramelized, about 2 minutes. Set aside to cool.

In a small bowl, mash the zest with the remaining 1 teaspoon sugar to release the oils. In the top of a double boiler, heat the half-and-half over simmering water until steaming. In a bowl, whisk the egg yolks until blended, then whisk in the honey and sugared zest, Whisk in about half of the hot half-and-half and pour the yolk mixture into the pan of half-and-half, Stir and cook over simmering water until the custard coats the back of a silicone spatula or spoon, about 10 minutes. Immediately place the custard pan in the ice bath and stir the custard occasionally until it cools to room temperature. Transfer to a container and stir in the cream. Cover and refrigerate until thoroughly chilled, about 3 hours.

Freeze in an ice cream maker according to the manufacturer's instructions. When the ice cream is almost frozen, spoon in the liqueur, if desired, and churn until blended in, about 1 minute more. Add the nuts and churn until blended in, about 15 seconds more. Transfer to a container, cover, and freeze until firm, about 2 hours.

Makes about 1 quart