Punch Hollandaise

A frozen punch rather than a sauce: a lemon-pineapple syrup churned to a coarse slush, then spiked and frozen again. The order of operations is the whole recipe.

• Add the spirits last, and mean itAlcohol depresses the freezing point, so brandy and gin stirred in at the start will leave you with cold syrup that never sets. Freeze to a slush first, then fold in the liquor and refreeze until firm enough to scoop.
• "Freeze to a mush"The original assumes a hand-cranked ice-and-salt freezer. In a modern kitchen, pour the strained syrup into a shallow metal pan, freeze, and rake it with a fork every 30 minutes until granular; or churn in an ice cream maker and transfer to the freezer.
• The can of pineappleCanned grated pineapple came in a range of sizes, so the quantity is genuinely open. About 2 cups of crushed pineapple with its juice matches the sugar and water here without swamping the lemon.
• Fifteen minutes of boilingFifteen minutes of cooking -- The recipe says only 'cook', but a fifteen-minute simmer will reduce the 4 cups of water somewhat and draw the oils out of the lemon rind. Use only the yellow zest, pared in strips, as white pith can turn the syrup bitter.
• StrainingStrain after cooling, not before, so the rind keeps flavouring the syrup as it drops in temperature. Press the pineapple pulp in the sieve if you want body; leave it loose for a clearer ice.
• Which ginTwo tablespoons of gin here may well have meant Holland gin (genever), maltier and rounder than a modern London dry, though the recipe does not say. A dry gin works but reads sharper against the pineapple.
• Yield and serviceExpect about 6 cups of finished ice, enough for 8 to 10 small servings. Frappe glasses are small stemmed glasses; any stemmed glass of 4 to 5 oz will do, set on a plate so the melt has somewhere to go.