In a mixing bowl, whisk milk, milk protein concentrate, sugar and vanilla extract until all ingredients are well dissolved.
Whisk in Greek yogurt, until smooth and fully incorporated.
Put freezer bowl in ice cream maker with paddle attachment. Turn ice cream maker on and pour mixture into bowl. Let ice cream maker churn mixture until frozen, for about 15 minutes.
While ice cream maker is churning, crush chocolate sandwich cookies in a sealed sandwich bag. You can use the bottom of a glass or rolling pin to crush the cookies.
Add in crushes cookies and churn until incorporated.
You can either enjoy the frozen yogurt immediately by serving in a bowl or ice cream cone, or you can freeze in popsicle molds.
If making popsicles, freeze for several hours. This ensures that the popsicle stick will not separate from the frozen yogurt bar when removing from the mold.
After frozen yogurt bars are completely frozen, run under warm water until they can easily be removed from popsicle molds.
Enjoy!