1. Make crust: Preheat oven to 350ºF. Mist a 9-inch springform pan with cooking spray. Wrap bottom and sides with 2 large foil pieces. Pulse cookies in a food processor until crushed. Pulse in butter. Press into an even layer in pan. Bake until firm, 8 to 10 minutes. Let cool.
2. Make filling: Place a roasting pan filled with 1 inch hot water on oven's center rack. Beat cream cheese until smooth. Add sugar; beat for 1 minute. Beat in eggs. Scrape down sides and bottom of bowl. Beat in vanilla, lemon juice and cornstarch.
3. Sprinkle Snickers over crust. Pour batter into pan; place in water bath. Bake until cake is set around edges but still jiggles in center, about 55 minutes.
4. Remove cake from roasting pan; remove foil. Place cake on a rack to cool. Cover and chill until firm, 4 hours or up to 1 day. When ready to serve, drizzle top with caramel sauce and top with chopped peanuts, if desired.