Before beginning this recipe, check to make sure that the dish or casserole you plan to use fits into your slow cooker.
Lightly coat a 1-quart soufflé dish or casserole with cooking spray. Tear off an 18x12-inch piece of heavy foil; cut in half lengthwise. Fold each piece lengthwise into thirds. Crisscross the foil strips and place the dish in the center of the crisscross; set aside.
For filling, in a large bowl, combine cream cheese, sugar, lemon juice, flour, and vanilla. Beat with an electric mixer on medium speed until well mixed. Beat in sour cream until smooth. Add eggs, beating on low speed just until combined. Stir in lemon peel.
Pour mixture into the prepared soufflé dish; cover tightly with foil. Pour the warm water into a 3 1/2- to 5-quart slow cooker. Bringing up the foil strips, lift the ends of the strips to transfer the dish to the cooker. Leave foil strips under dish.
Cover and cook on high-heat setting for 2 1/4 to 2 3/4 hours or until center is set.
Carefully lift with foil strips to remove dish; discard foil strips. Cool completely on a wire rack. Cover and chill for 4 to 24 hours. To serve, spoon cheesecake into dessert dishes. If desired, garnish with raspberries.