Combine all of the ingredients in a saucepan. Heat over medium-high heat and bring to a simmer. Reduce the heat and allow to simmer for 35 minutes, or until it has reduced in half and thickened. Make sure to whisk occasionally to avoid any sticking to the bottom of the pan.

Transfer to an airtight container and allow to cool completely. Once cooled, cover and place in the refrigerator for at least 2 hours before serving. Can be stored in the refrigerator for up to 3 weeks.

Add a paper filter to a pour-over brewer. Pour water, just off boiling, to wet the filter and warm the brewing container. Discard the water. Set the damp filter aside and add the ice to the brewing container.

Place the filter back on the pour-over brewer and add the ground coffee. Shake or stir slightly to level the top of the grounds. Pour 50 grams of water just off boiling, carefully wetting all the grounds. Stir slightly, then let sit for 40 seconds.

Slowly add the rest of the water, pouring in careful circles. Try to avoid pouring directly in the center or down the sides of the filter. Let the rest of the water drain through the coffee grounds. It should take roughly 3 to 4 minutes for all the water to pass through. If it took too long, use less coarse coffee grounds. If it took too quickly, use finer grounds.

Discard the coffee grounds, add 3 to 5 tablespoons of sweetened condensed milk, and stir. Split between two cups to serve.