In a large bowl, beat 1 ¼ cups cream cheese until smooth. I use a hand whisk, but you can use an electric mixer at low speed. Add ¾ cup sour cream and mix well.
Add ¼ cup brown sugar and mix until well combined.
Add 2 eggs and 1 teaspoon vanilla extract and stir until well without beating. Use a whisk to integrate well. We don't want to incorporate unnecessary air so the cheesecake bakes without puffing up much.
Add ¾ cup regular dulce de leche, pinch of salt and ¼ cup heavy cream. Mix until well combined and the mixture is even in color. Don't beat.
Pour the batter into the prepared pan.
Bake for 10 minutes at 325°F (170°C). Lower the temperature to 275°F (140ºC) and bake for about 40 minutes. It might be more, depending on the oven.
It should still be a little jiggly in the middle (flan type), with the edges a little puffed with some cracks. Turn off the oven and leave the door ajar with the cheesecake inside for 20 more minutes.
Turn off the oven and leave it inside for 20 more minutes.
Let it cool completely on a wire rack.
Wrap the pan in plastic wrap or aluminum foil and put it in the refrigerator for at least 6 hours. I like to make cheesecakes the day before. At this point, you can keep it in the fridge for 3 days or freeze it for a month, always well-wrapped.