Set a kettle on to boil; you will need 1 cup of boiling water to dissolve the jello.

Lightly coat a jello mold with baking spray and set aside.

Strain the mandarin oranges, reserving the liquid (it should be about ¾ cup; if not, fill it up to ¾ cup with water).

Pour 1 cup of boiling water over the orange jello mix and whisk until fully dissolved.

Add the reserved mandarin liquid and ½ cup cool water; mix to combine.

Stir in ½ cup sweetened condensed milk until fully incorporated.

Pour the gelatin mixture into the prepared mold and top with the mandarin orange segments.

Refrigerate until firm, about 4 hours.

To un-mold the jello, fill a sink with warm water; dip the mold in for 15–20 seconds.

Place a plate or serving platter on top and quickly invert the mold; if the mold has two parts, separate them.

Serve in slices.