Line an 8-inch square baking pan with foil, leaving at least a 1-inch overhang on all sides. Mist with cooking spray.
Fry bacon crispy being careful not to burn it. Remove from pan and place onto paper towels to cool. When cool, break or use kitchen scissors to cut bacon into small pieces, throwing away any fatty pieces.
Combine brown sugar, marshmallow fluff, evaporated milk, butter and salt in a heavy saucepan. Cook over medium heat, whisking often, until it comes to a boil. Let it boil for 5 minutes, stirring constantly to prevent scorching
Remove pan from heat, stir in white chocolate chips until fully melted and mixture is smooth. Stir in walnuts, bacon and maple extract. Quickly pour into baking pan and smooth top. Refrigerate uncovered until firm, about 2 hours.
Using foil handles, lift fudge from pan and place on cutting board. Remove all foil. Cut fudge into pieces wiping off knife between cuts. Serve immediately, or store in an airtight container in the refrigerator. Place waxed paper between layers. Can be stored for up to 1 week.
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