Step 1 – Prepare the Oven & Pan
Preheat the oven to 350°F (175°C).
Have an 11-inch pie dish ready.
Because this recipe makes a generous amount of filling and crust, an 11-inch dish is ideal. If using a smaller pie dish, don't force all the filling into it.
Make the Graham-Vanilla Wafer Crust
Step 2 – Crush the Cookies
Process the graham crackers and Nilla Wafers separately or together until they become fine crumbs.
Measure 1 cup of each after crushing.
Step 3 – Combine the Crust
In a medium bowl, combine:
- Graham cracker crumbs
- Nilla Wafer crumbs
- Brown sugar
Pour in the melted butter.
Stir until all the crumbs are evenly moistened and resemble wet sand.
Step 4 – Press Into the Pie Dish
Transfer the mixture to the pie dish.
Using the flat bottom of a measuring cup, firmly press the crumbs across the bottom and up the sides.
Try to keep the thickness relatively even, particularly where the bottom meets the sides.
Step 5 – Bake the Crust
Bake at 350°F (175°C) for 10 minutes.
Remove from the oven and let the crust cool while you prepare the filling.
Keep the oven at 350°F.
Make the Key Lime Filling
Step 6 – Combine the Creamy Ingredients
In a large bowl, combine:
- Key lime juice
- Sweetened condensed milk
- Heavy whipping cream
- Sour cream
Whisk until smooth and completely combined.
The mixture will naturally begin thickening as the acidic lime juice interacts with the dairy.
Step 7 – Add the Flavorings
Add the lime zest and vanilla bean paste.
Whisk gently to combine.
Step 8 – Add the Egg Yolks
Add the egg yolks.
Whisk gently until they're completely incorporated and the filling looks smooth and uniform.