12 graham crackers
1 1/2 cups granulated sugar, divided
1/4 teaspoon kosher salt
5 tablespoons unsalted butter, melted and cooled, plus more for greasing pan
4 (8-ounce) packages cream cheese, at room temperature
1/2 teaspoon vanilla extract
4 large eggs
1/2 cup sour cream
1/2 cup prepared dulce de leche
Flaky sea salt, for garnish
Preheat oven to 350°F. Wrap 3 layers of aluminum foil around the outside of a 9-inch springform pan with 3-inch-high sides. Grease pan with butter. Combine graham crackers, 1/4 cup sugar, and salt in a food processor and pulse until crumbly. Add melted butter, and pulse until moistened. Press crumb mixture evenly onto bottom and 1 1/2 inches up sides of prepared pan.
Bake in preheated oven just until golden brown, about 15 minutes. Let cool completely. Reduce oven temperature to 325°F.
In an electric mixer fitted with the paddle attachment, beat cream cheese on medium speed until fluffy. Add vanilla and remaining 1 1/4 cups sugar, and beat until combined.
Add eggs, 1 at a time, beating until well combined after each addition. Add sour cream, and beat until smooth, about 35 seconds. Measure 1 cup filling, and place in a medium bowl.
Add dulce de leche to filling in bowl; whisk until dulce de leche is fully incorporated into filling. Pour plain cheesecake filling into cooled crust. Drizzle dulce de leche filling over top. Using a knife, swirl to create a marbled effect.
Set cheesecake in a large baking pan. Add hot water to baking pan to come 1 inch up side of springform pan. Bake until almost set (the center will move slightly when the pan is gently shaken) but not puffed, about 1 hour and 30 minutes.
Let cheesecake cool at room temperature 2 hours. Cover loosely with plastic wrap, and refrigerate until completely cooled, at least 6 hours or preferably overnight. Garnish with sea salt, if desired.