Crush the digestive biscuits into fine crumbs using a food processor or zip bag with a rolling pin. Mix with melted butter and sugar until combined. Press the mixture evenly into the bottom and sides of a 9-inch pie dish. Chill in the fridge for 10 minutes.

Preheat your oven to 175°C (350°F). Chilling the crust first helps it hold shape while baking.

Place the chilled crust in the oven for 10–12 minutes. Remove and let it cool. Baking the crust gives it a slightly crisp texture that contrasts beautifully with the creamy filling.

In a mixing bowl, whisk together the egg yolks, sweetened condensed milk, lime juice, lime zest and vanilla extract. Mix until smooth. The mixture should be thick, creamy and glossy.

Pour the lime filling into the cooled crust. Spread evenly using a spatula. Ensure it reaches all corners for a uniform pie.

Return the pie to the oven and bake for 12–15 minutes. The filling should be set but still slightly jiggly in the center. Remove from the oven and cool to room temperature.

Place the pie in the refrigerator for at least 2 hours. Chilling helps the filling firm up and enhances the flavor. This step is essential for a perfect sliceable pie.

Whip the heavy cream with powdered sugar until soft peaks form. This will create a smooth and light topping for the pie.

Pipe or spread the whipped cream over the chilled pie. Sprinkle extra lime zest on top for decoration. This adds color and enhances the lime aroma.

Slice the pie carefully with a sharp knife. Serve chilled and enjoy the bright, tangy flavor with every bite. This is the best way to experience how to make Hairy Bikers Key Lime Pie.