The faster way to defrost peaches is to use the defrost setting on the microwave or use a 50 percent power setting. Usually the peaches will be thawed in about 3-5 minutes, but it can take slightly longer if they are frozen as a solid block of ice. You can also place the bag of frozen peaches and run it under cool water to defrost them in about an hour and a half to two hours. Frozen peaches can also be thawed in the refrigerator for about 6-8 hours or overnight. This method will allow the fruit to be the most firm of the three methods and less mushy. While some recipes keeping the fruit from being mushy is important, since we are cooking the peaches in a cobbler the baking process will cause the peaches to be a but mushy as they cook anyways. So defrosting peaches slowly isn't as important for this recipe.