Sprinkle gelatin over 1/4 cup of the milk in blender container; let stand 2 min. or until gelatin is softened. Meanwhile, heat remaining 3/4 cup milk in saucepan or microwave.
Add to gelatin mixture; cover. Blend on low speed until gelatin is completely dissolved.
Add peanut butter, sugar and ricotta cheese; cover. Blend on high speed until smooth. Refrigerate until mixture mounds slightly when dropped from a spoon.
Spoon into pie crust.
Refrigerate 3 hours or until set.
Cut into 10 slices to serve. Top each serving with about 1 Tbsp. of the whipped topping and a sprinkling of peanuts. Store leftover pie in refrigerator.