Line a 9- by 13-in. pan with foil, letting foil hang over edges. Set aside. In a bowl, combine chocolate, butter, and espresso.
In an 8- to 10-qt. pan, combine sugar, corn syrup, and milk, then bring to a boil over medium heat. Cook, stirring often with a wooden spoon to prevent boiling over, until mixture reaches 235° on a candy thermometer, about 15 minutes.
Remove pan from heat and pour chocolate mixture into hot milk. Stir until smooth. Add almonds, stir just until combined, then pour fudge into prepared pan, smoothing top with spoon. Chill at least 2 hours.
Invert fudge onto a cutting board and peel off foil. Cut fudge into 1-in. squares.
Make ahead: Up to 1 week, chilled airtight, or up to 2 months, frozen.
Note: Nutritional analysis is per piece.