What you will need: 
1 - .3-oz box sugar free lime flavor gelatin
¼ cup boiling water
2 containers (8 oz each) Key Lime Pie flavor light yogurt
1 container (8 oz) frozen fat free whipped topping
1 - 9” reduced fat graham cracker pie crust 

How to prepare:
In large bowl, dissolve gelatin in boiling water. 
With wire whisk, stir in yogurt with wooden spoon, fold in whipped topping. 
Transfer mixture to pie crust, refrigerate overnight.