Many thanks to all of you for your thoughtful responses. I don't recall heating the cream for this recipe. I am, however, definitely prone to over-churning and, occasionally, overheating my milk/cream. I will post again if I puree the thawed ice cream (I may just eat the rest of it as is, as it's still delicious) and if my next batch is butter-chunk free from less churning. I appreciate your help!

betteirene, any chance it could also be caused by over-heating the milk/cream instead of just scalding it? Know that too much heat will start to get cream to clot...

Thanks betteirene for your thorough responses -- I never knew that about cream and milk and churning. I was going to propose the same solution -- thawing the ice cream slightly and pureeing in a food processor. Mwb, thanks for your patience, and really glad you asked foodpickle rather than just feeling disappointed! Hope our responses help.

I forgot to add that the only ways I can think of to remove the chunks of butter is to soften the ice cream it slightly and attack it with a hand-held blender or to pulse it quickly in a food processor and refreeze; or to place the frozen block in a sieve placed over a bowl and allow it to melt, then discarding the butterfat and churning the mixture again.

Perhaps, when the book is reprinted, the recipe title could be changed to "Blueberry Butter Chunk Ice Cream." (With a wink and a nod to Ben & Jerry.)

Usually, when only heavy cream is used to make ice cream, all the churning leads to butter. That's why most recipes for homemade churned ice cream (including super premium ones) often call for milk in addition to the cream. Most of the time, the answer to the problem of butter chinks is to cut the whipping cream by at least half and replace that amount with regular milk. The cream in that particular recipe, however, is cut by the blueberry syrup, so too much butterfat is not the problem.

That leads to too much churning as your likely culprit. Ignore the command to follow the instructions from the manufacturer of your freezer; instead, churn it only until it becomes the consistency of mashed potatoes, usually about 15 minutes.

This recipe from Merrill for lime ice cream does not call for a freezer, nor does it instruct you to stir the slush with a fork every half-hour. Even though it uses only pure cream, lime juice and zest and sugar, it's tart-sweet creaminess rivals that of any super premium brand sold in a pint. The recipe is failure-proof precisely because it is not churned. http://www.food52.com/recipes/5438_the_best_lime_ice_cream