1Combine yogurt, sugar, peanut butter, Irish cream liqueur, and vanilla extract together in a bowl. Refrigerate yogurt mixture until chilled, 30 to 45 minutes.
2Process yogurt mixture in an ice cream maker according to manufacturers' instructions for churning.
Footnotes
Cook's Note:
Peanut butter may remain a bit chunky when stirring all the ingredients together. I use a rubber spatula.
My Kitchen-Aid(R) ice cream maker attachment took about 25 minutes to churn the frozen yogurt.
'Froyo' will be a soft-serve. If you want it more firm, place in an airtight plastic container and freeze for 2 to 4 hours.