Begin by crushing the digestive biscuits into fine crumbs using a food processor or a rolling pin. Combine the crumbs with ½ cup melted unsalted butter in a mixing bowl, ensuring even distribution. Press this mixture firmly into the bottom of an 8-inch springform pan, creating a solid layer. Chill the crust in the refrigerator for 30 minutes to set.

In a medium saucepan, combine 1.5 cups of sugar and ¼ cup water, cooking over medium heat. Stir gently until the sugar dissolves, then increase the heat and boil until the mixture turns a deep amber color, about 8-10 minutes. Remove from heat, then carefully whisk in ¾ cup whipping cream, 3 tbsp butter, 1.5 tsp sea salt, and 2 tsp vanilla extract until smooth. Let the sauce cool to room temperature.

In a large mixing bowl, beat 21 oz of softened cream cheese using an electric mixer until smooth. Gradually add ¼ cup powdered sugar and the remaining ½ tsp vanilla extract, mixing until fully incorporated. Gently fold in the cooled caramel sauce, ensuring an even mixture, then add 1 cup of whipped cream, folding delicately to maintain the fluffiness. Finally, fold in the chopped Twix bars until evenly distributed.

Pour the creamy filling over the chilled biscuit crust, using a spatula to spread it evenly. Tap the pan gently on the counter to remove any air bubbles. Cover with plastic wrap and refrigerate the cheesecake for at least 4-6 hours, or preferably overnight, until it is firm and set.

Once the cheesecake is set, take ½ cup of salted caramel sauce and spread it over the top of the filling. In a small saucepan, heat 1 cup of whipping cream until just simmering, then pour it over 4 oz of finely chopped semisweet chocolate in a bowl. Let it sit for 2 minutes, then stir until smooth and glossy. Pour this ganache over the caramel layer, making sure to cover it completely, and chill until set, about 1 hour.

To serve your No Bake Twix Cheesecake, carefully release it from the springform pan. Use a heated knife to slice through the rich layers with ease. If desired, garnish with extra chopped Twix bars or caramel shards for added texture. Serve chilled.