mix crust ingredients and press into a 9 or 10 in springform pan.
grease sides of pan with melted butter- this is important!
preheat oven to 325 with a baking dish of water on the bottom rack (move to lowest position) and move upper rack to second highest position.
beat cream cheese, adding sugar at medium low speed. scrape sides as needed (if you have a mixer with paddle attachment, use it!) until smooth.
on low speed add milk until combined.
add eggs one at a time until combined.
add lemon, vanilla and sour cream.
sift in flour and cornstarch, mix just until combined (still on low).
pour into crust.
bake on higher rack- DON'T open oven before one hour ever!
check on it at 1 hour 5 minutes, if it's set outside but jiggles, not liquid, but definitely shakes) inside, it's done. it usually will need 1 hour 15 minutes at least. the edges should be just turning golden.
TURN OFF oven leave door closed, no more peeking for at least one hour, preferably 3.