In a large nonreactive saucepan, combine the goat's milk, buttermilk, and rennet. Heat over low heat until the mixture reaches a temperature of 180 degrees F. Transfer to a nonreactive bowl and allow to sit overnight, covered, until the curds and whey separate. Line a colander with several layers of cheesecloth and ladle the curds into the colander. Discard whey. Fold cheesecloth over top of curds and allow to drain overnight, refrigerated.
Remove cheesecloth and season, to taste, with olive oil and salt and pepper, if desired.