Make the Crust:

1. Preheat Oven:
   Preheat your oven to 350°F (175°C). Line a muffin tin with cupcake liners or grease it well.
2. Prepare the Crust Mixture:
   In a bowl, combine graham cracker crumbs, sugar, and melted butter. Mix until the crumbs are evenly coated and resemble wet sand.
3. Form the Crusts:
   Spoon about 1–2 tablespoons of the mixture into each muffin cup. Press down firmly with the back of a spoon or the bottom of a glass to create an even layer.
4. Bake the Crusts:
   Bake for 5–7 minutes, until lightly golden. Remove from the oven and let cool while you prepare the filling.

Make the Filling:
5. Mix the Key Lime Filling:
In a bowl, whisk together the egg yolks, sweetened condensed milk, lime juice, and lime zest until smooth.

6. Fill the Crusts:
   Spoon the filling evenly into the cooled crusts, filling each about 3/4 full.
7. Bake the Mini Pies:
   Return the muffin tin to the oven and bake for 10–12 minutes, or until the filling is set but still slightly jiggly in the center. Let cool to room temperature, then refrigerate for at least 1 hour.

Make the Whipped Cream:
8. Whip the Cream:
In a mixing bowl, beat the heavy whipping cream and powdered sugar until stiff peaks form.

9. Decorate the Pies:
   Pipe or spoon whipped cream onto the chilled mini pies. Garnish with lime slices, zest, or a sprinkle of graham cracker crumbs.

Serve:
10. Enjoy:
Serve chilled and enjoy these tangy, creamy bites of goodness!