Beat 12 ounces regular cream cheese in a large mixing bowl until very smooth. You can use a handheld electric mixer at low speed, or a wire whisk. If the cheese is at room temperature, mixing it by hand should not be a problem. We don't want to incorporate too much air into the batter.
Gradually add ⅔ cup sugar and mix until it's well incorporated. If using a handheld electric mixer, use it only until this part and at low speed.
Add 2 eggs all at once, mixing with a wire whisk until completely combined, scraping down the sides of the bowl a few times. Be patient as the egg white sometimes takes a little longer to dissolve, and don't be tempted to beat. This is good for creaminess later.
Add ⅓ cup heavy cream, ¾ teaspoon vanilla, and ¼ cup regular sour cream, stirring to incorporate well. You must have a lump-free batter.
Scrape the mixture with a rubber spatula into the baked crust (it might still be warm, and that’s fine).
Bake cheesecake pie for about 40 minutes, until the top is dry, but the filling still jiggles quite a bit in the center. It might take you a little longer (as a reader reports), but don't be tempted to bake it until the center is set or almost set. It will solidify as it cools and after it’s refrigerated. Turn off the oven and let the pie inside for 15 more minutes.
Then cool completely to room temperature in the pie plate on a wire rack. Cover in plastic wrap (still in the pan, see Note below) and refrigerate for at least 8 hours. It's essential to chill it for several hours before eating it. Remove the plastic when you want to serve it. I leave it for 1 or 2 days for the creamiest consistency.
Serve semi-cold or at room temperature, plain or with a topping (see Notes below for ideas).
Store leftovers covered in plastic wrap or in an airtight container in the refrigerator for 4-5 days or frozen for up to a month. For the freezer, I wrap it in cling film first and then aluminum foil. Defrost at room temperature or in the fridge, depending on how much time you have.