Heat the cranberries with 1/4 cup sugar, and the orange juice and orange zest, in a medium saucepan over medium heat. When hot, stir to dissolve the sugar. Bring to a simmer and adjust the heat so the mixture will simmer until the cranberries burst and the mixture has thickened, about 5 minutes. Transfer the cranberry mixture to a nonreactive container, then cool uncovered in the refrigerator.

Melt the chopped white chocolate and 1/2 cup of half-and-half in the top half of a double boiler or in a medium glass bowl in a microwave oven, and stir until smooth. Set aside.

Heat the heavy cream and the remaining 1 cup of half-and-half with 1/4 cup of sugar in a large saucepan over medium heat. Stir to dissolve the sugar. Bring to a boil, about 5 to 6 minutes, then remove from the heat.

Place the remaining 1/2 cup of sugar and the eggs in a medium bowl. Whisk until thoroughly combined. Ladle 1/2 cup of the hot cream mixture, 2 tablespoons at a time, into the egg mixture and whisk gently to incorporate.

Pour the egg and cream mixture into the remaining cream mixture in the saucepan and whisk until thoroughly combined. Add the melted chocolate mixture and whisk until combined. Heat over medium heat, stirring constantly. Bring to a temperature of 185 F (use a digital thermometer for an accurate temperature reading of the mixture).

Pour the chocolate mixture through a fine gauge strainer into a large bowl. Cool in an ice-water bath to a temperature of 40 F to 45 F.

When the mixture is cold, freeze in an ice-cream machine following the manufacturer's instructions. Transfer the semifrozen ice cream to a 2-quart plastic container. Fold in the chilled cranberry mixture until evenly distributed. Securely cover the container, then place in the freezer for several hours before serving. Makes 1 1/2 quarts.