White Chocolate-Swirled Malted Milk Fudge

Line an 8-inch square baking dish with heavy-duty aluminum foil, allowing at least a 2-inch overhang on 2 sides. Lightly grease foil with butter; set dish aside.

Stir together sugar, cocoa blend, ground espresso beans, and salt in a heavy 5-quart saucepan. Stir in whole milk until well combined. Bring mixture to a rolling boil over medium, stirring constantly, 12 to 16 minutes. Insert candy thermometer; boil, without stirring, until thermometer registers 234°F (soft-ball stage), 12 to 16 minutes.

Place white chocolate in a small microwaveable bowl. Microwave on HIGH until melted and smooth, about 40 seconds, stirring every 15 seconds. Set aside.

Once cocoa mixture reaches 234°F, remove from heat, and remove candy thermometer. Add marshmallows, malted milk powder, butter, and vanilla. Using a wooden spoon, stir mixture until smooth and thickened but still pourable, about 7 minutes. Pour mixture into prepared baking dish. Drizzle white chocolate over top, and pull a small offset spatula through mixture to create a swirled pattern. Let cool, uncovered, at room temperature until hardened, at least 4 hours or up to 8 hours or overnight.

Using foil overhang as handles, lift fudge from baking dish; discard foil. Transfer fudge to a cutting board, and cut into 1 1/2-inch squares. Serve immediately, or store in an airtight container up to 2 weeks.