"A cold-cut sandwich on a long roll" would look like this:
It's a strange passage because the writer has gone to great length to AVOID using common colloquial terms and brand names in the first and third sentence. Yet she uses the brand name "Milk-Bone" in the second sentence. It would have been more natural to write
"On the kitchen island sat a Saran-wrapped plate holding a Italian sub. Beside it lay a Milk-Bone. The Post-It note read..."
"Saran wrap" was the first plastic cling-film and it has become a generic name. An Italian sub, at least around here, means Italian cold cuts like salami and prosciutto on a "sub" (short for "submarine") roll. "Post-It notes" were the first brand of yellow sticky notes, invented by 3M.