Prepare an 8 x 8-inch square pan by laying two sheets of parchment paper across it (forming a plus sign). This will make it easy to remove and cut the fudge later.
Melt the chocolate and milk together in a saucepan over low heat. Stir in almond extract, if using.
Spread into pan, using a spatula to even it out. Sprinkle on sea salt. Chill in refrigerator for at least two hours, until set.
Once set, remove from pan and cut into pieces. Stores well in a sealed container in the fridge, with waxed paper between layers.