Stir the coffee grounds and water together in a large jar, then cover and refrigerate for at least 12 hours, or up to 72.

Place a fine mesh strainer over a bowl, then line it with a coffee filter, cheese cloth or a few layers of paper towels. Pour the coffee mixture through and allow it to slowly drain. This may take up to 30 minutes to fully drain, so be patient.

Discard the coffee grounds (compost them!), then whisk the liquid with sweetened condensed milk.

Pour into a 10-popsicle mold, cover, and insert popsicle sticks. Freeze until solid, at least 6 hours or overnight.

Run the popsicle mold under hot water for about 30 seconds to loosen, then remove the pops and serve immediately or store for later. Wrap tightly with plastic wrap, then store in a zip-top bag in the freezer for up to 3 months.