Turn the oven down to 325 °F (163 °C).
In a large mixing bowl, beat the cream cheese and sugar using an electric hand mixer at medium speed. Beat just until well combined and creamy.
24 ounces (680 grams) full-fat cream cheese, 3/4 cup (150 grams) granulated sugar
Mix together the milk and cornstarch until no lumps remain. Add this and the remaining ingredients to the cream cheese mixture. Beat on low until well incorporated. Overbeating will make cracks so don't overmix.
5 tablespoons milk of choice, 3 tablespoons cornstarch, 1 tablespoon lemon juice, 2 teaspoons vanilla extract, 1/4 teaspoon salt
Pour over the crust. It was the perfect amount for the both crusts. If you have too much filling, don't pour it over the crust.
Bake for 35-40 minutes (using a pie pan will be closer to 40). The middle will still be a little jiggly.
Remove to a rack to cool for 2 1/2 hours.
Use a knife to run around the inside of the pan to loosen the crust from the pan.
Chill for at least 4 hours before cutting.
If the homemade oat crust is very firm and too difficult to cut straight from the fridge, let the cheesecake sit at room temperature for 20-30 minutes.
Cover and refrigerate any leftovers for up to 5 days. It can also be frozen whole or in pieces and thawed overnight in the fridge.