Place white chocolate in a stainless steel bowl over a double boiler of 120°F water until chocolate is melted. Stir occasionally to maintain a liquid state. In a saucepot over medium heat, combine cream, half-and-half, vanilla and nutmeg. Bring to 190°F or a very low simmer. Do not boil. In a separate stainless steel mixing bowl, whisk eggs and sugar until well blended. Slowly add hot cream mixture into egg mixture, one ladle at a time, stirring constantly to prevent eggs from scrambling. Continue whisking and pour melted chocolate into custard until blended. Pour mixture back into saucepot over medium-high heat, stirring constantly until temperature reaches 190°F. Do not boil because eggs will scramble. Strain mixture through a fine sieve and refrigerate, preferably overnight. When fully chilled, place contents in a home-style ice cream maker and follow manufacturer's directions. When custard is half frozen, add puréed blueberries and continue to churn. NOTE: You may wish to blend puréed blueberries into frozen ice cream after done as a swirl.