Preheat oven to 375°F. Lightly spray a 9.5 inch deep dish pie dish with cooking spray.
In a small bowl, mix together graham cracker crumbs, sugar, almonds and butter Press crumb mixture into pie dish. Bake for 8 minutes. Cool completely.
Key Lime Filling: Preheat oven to 325°F Using an electric mixer, whip together egg yolks on high speed until fluffy and thickened, around 3-5 minutes. Gradually add condensed milk and lime juice. Add sour cream, zest and vanilla on low speed, mixing until fully combined.
Pour into baked graham cracker crust and smooth the top.
Bake for 30 minutes or until the center is set when gently shaken. Let pie cool at room temperature slightly before chilling. Chill for at least 4-6 hours.
To make whipped cream: (Just before slicing and serving)Beat heavy cream and sugar together using an electric mixer until stiff peaks form. Beat in vanilla. Spread or pipe the whipped cream on top of the cooled pie.
Top with additional lime zest. if desired.