Preheat oven to 325 F/163 C. Place a 10" springform cheesecake pan on a rimmed baking sheet.
In a food processor, pulse cookies until finely ground. Add melted butter, and pulse to moisten. Transfer to springform pan, and press crumbs firmly and evenly into the bottom (use the bottom of a metal measuring cup to help). Bake for 10 minutes, and set aside.
Wipe out bowl and blade of food processor. Add cream cheese, sugar, and salt; blend until smooth. With processor running, add eggs one at a time. Pour mixture into stand mixer (or mix by hand), then add sour cream, flour, and finally melted chocolate. Blend filling until smooth, scraping down sides of bowl as needed.
Pour filling into pan over prebaked crust. Place baking sheet with cake pan in oven. Bake at 325 F/163 C until set (puffed up around the edges and center is set, but slightly wobbly), about 1 hour. Turn oven off, and let cheesecake sit 1 hour in oven, without opening door.
Run a knife around the edge of the pan just to loosen sides, then cool completely on wire rack. Cover loosely and refrigerate at least 6 hours or overnight. Cut with a wet knife for the cleanest cuts, and store covered in the refrigerator or in a container/ziptop bag in the freezer, slices separated by waxed paper.