Preheat the oven to 350°F.

Prepare the custard mixture by combining the whole eggs, egg yolks, dulce de leche, evaporated milk, heavy cream and salt in a blender. Blend on high speed for 30 seconds. Leave the mixture in the blender and set it aside.

Prepare the caramel syrup by heating the sugar in a saucepan over medium heat. As the sugar gets hot, it will start to liquefy - you'll notice a pool of amber liquid around the edges. Lower the flame slightly and stir until sugar is completely melted. The sugar will clump as it melts but will eventually turn smooth. Watch the color as you keep stirring, turn the flame down lower if it starts to get dark too quickly.

Quickly pour the caramel syrup into an aluminum pan or mold. Using oven mitts, tilt the pan so the syrup covers the bottom and sides of the pan. Allow the syrup to harden.

Place the mold with the hardened syrup in a roasting pan. Pour the custard mixture into the mold and cover it with foil. Fill the bottom of the roasting pan with 1-2 inches of boiling water, add a little more water if you're using a deep mold.

Transfer the roasting pan to the oven and bake the flan at 350°F for 1 hour and 15 minutes.

Remove the roasting pan from the oven and let cool for 15 minutes before removing the flan from the water bath. Once out of the water, let it finish cooling at room temperature - another 15 minutes. 

Transfer the flan to the refrigerator and let chill for at least 4 hours, or overnight.

After the flan has chilled and set, remove it from the refrigerator and place the mold in a shallow pan of hot water. Let it sit for about 10 minutes. This step is important because it helps release the flan from the pan.

Flip the flan onto a pie plate or a dish with raised sides. Let it sit inverted until it releases itself - this might take a few minutes! Cut into slices and serve.