Lay the can on its side in a large, deep pot. Fill the pot with room-temperature water, ensuring the water level is at least 2 inches above the can. It's crucial that the can remains fully submerged throughout the simmering process to avoid warping or splitting, which could lead to dangerous spills.

Place the pot over high heat and bring the water to a simmer. Reduce the heat to maintain a gentle simmer and cook for 2 hours if you prefer a light, golden caramel. For a deeper, richer caramel, continue simmering for up to 3 hours. Every 30 minutes, check the water level to ensure the can remains under at least 2 inches of water; add boiling water as needed.

When done, carefully remove the can from the water with tongs and place it on a wire rack to cool to room temperature. Avoid opening the can while it’s still hot, as the pressurized caramel can spray out and cause burns.

Unopened cans of dulce de leche can be stored at room temperature for up to 3 months. Once opened, scoop out the dulce de leche and, if desired, reheat in a double boiler until it reaches a smooth, spreadable or drizzle-able consistency. Transfer any leftovers to an airtight container and refrigerate for up to 3 weeks.