Preheat the oven to 350 degrees F

Tightly wrap the outside of a 9-inch diameter springform pan with 3 layers of heavy-duty foil

Mix the almonds, cracker crumbs, and sugar in a food processor until finely ground. Add the butter and process until combined and moist crumbs are formed

Press the almond mixture onto the bottom of the prepared pan (not up the sides)

Bake the crust until it is set and beginning to brown, about 12 minutes. Cool. Decrease the oven temperature to 325 degrees F.

Melt the white chocolate gently over simmering water or on low heat in the microwave.

Using an electric mixer, beat the cream cheese, mascarpone cheese, melted chocolate, sugar and salt in a large bowl until smooth, occasionally scraping the sides of the bowl with a rubber spatula.

Beat in the vanilla.

Add the eggs, 1 at a time, beating just until blended after each addition.

Pour the cheese mixture over the cooled crust in the pan.

Place the springform pan in a large roasting pan. Pour enough hot water into the roasting pan to come halfway up the sides of the springform pan.

Carefully put the pan into the oven and bake until the center of the cheesecake moves slightly when the pan is gently shaken, 55 minutes (the cake will become firm when it is cold).

Remove the cake from the oven, top with the sour cream topping and return to the oven for 12 more minutes.

Transfer the cake to a cooling rack and cool for 1 hour.

In a small, heavy bottomed pot, melt the sugar with water. Cook over high heat until deep amber in color; do not stir. Remove from heat, and carefully whisk in the cream (it will bubble up considerably; make sure you use a larger pot than you think you will need!). Whisk in the butter; returning the pan to low heat if necessary to get the butter to melt.

Add the Chocolate Liqueur to taste and let cool to room temp. Spread over the top of the cheesecake with a thin layer of the caramel.

Lightly sprinkle the top with Maldon sea salt.

Refrigerate until the cheesecake is cold, at least 4 hours and up to 2 days.