In a bowl, whip egg yolks, lime juice, and milk. Place bowl over a pot of boiling water and whip while cooking for 10-12 minutes until slightly thick and smooth. In a small bowl, mix gelatin with water, stir, and let sit for 5 minutes. Add gelatin to bowl on stove and whip. Remove bowl from heat and set over a large bowl of ice, stirring occasionally until cool. In a new bowl, whip cream with a mixer on high speed. Slowly add powdered sugar and vanilla. Whip for 7-8 minutes until stiff. With a rubber spatula fold in 1/3 of whipped cream into lime mixture. Continue folding in remaining whipped cream until smooth. Pour into pie crusts and cool in refrigerator for at least two hours. Serve. Makes two 10” pies.