Creating Torta de Limão Trufada is a delightful process. Follow these steps to ensure a perfect dessert:

1. Preheat Oven: Preheat your oven to 180°C (350°F).
2. Prepare the Crust: In a mixing bowl, combine the crushed biscuits, melted butter, and sugar. Mix until combined. Press the mixture firmly into the bottom of a 9-inch springform pan to form an even layer.
3. Bake the Crust: Bake the crust in the preheated oven for 10 minutes. Remove and let it cool completely.
4. Make the Lemon Filling: In another bowl, whisk together the lemon juice, lemon zest, sugar, eggs, and condensed milk until smooth.
5. Cook the Filling: Pour the lemon filling over the cooled crust. Bake for 25-30 minutes or until the filling is set but still slightly jiggly. Remove from the oven and let cool.
6. Prepare Chocolate Topping: In a saucepan, heat the heavy cream until just boiling. Pour it over the chopped dark chocolate and let it sit for about 5 minutes. Stir until smooth. Mix in the butter until fully combined.
7. Pour Over Lemon Filling: Gently pour the chocolate mixture over the cooled lemon filling, spreading it evenly.
8. Chill: Refrigerate the torta for at least 30-60 minutes to set the chocolate topping.
9. Remove from Pan: Carefully remove the sides of the springform pan before serving.
10. Decorate (Optional): You can garnish with lemon slices or chocolate shavings for an elegant touch.