Preheat oven to 350 degrees; place pan of water on lowest rack in oven - this helps prevent the cheesecake from cracking during baking.
In large mixing bowl beat cream cheese until fluffy. Gradually beat in sweetened condensed milk until smooth. Beat in eggs, one at a time, then sour cream and vanilla.
Pour into 9-inch spring form pan. Bake 50-55 minutes until edges are light golden brown. The center will still be very slightly soft. Let cool, then refrigerate at least 4 hours to chill completely before serving.
If not doing the Chex crust I recommend 1½ cups GF shortbread cookie crumbs plus 2-3 tbsp butter for a wonderful crust