In medium bowl with fork, mix/mash together grated cheese and enough of yogurt to make mixture that holds together well; shape into about 2 dozen (1-inch) balls.
In another bowl, mix together pistachios and cranberries. Roll each ball in mixture, pressing in firmly to coat. Cover and refrigerate until ready to serve. Just before serving, insert small piece of rosemary in each ball if desired.
Cheddar, Pistachio & Cranberry "Pops"
Makes about 2 dozen appetizers or 12 appetizer servings