If so, then she would be displaying extreme ignorance of medical practice as it relates to victims of poisoning, especially when the victims tell the doctors what they had eaten recently. Mushrooms would (and did) set off huge alarms.
It would also suggest that she intended just to make everyone sick for whatever malevolent reason, in which case the subsequent deaths would have surprised/shocked her.
Probably A LOT of ignorance.
And good on the hospital for pressing -- but naturally, they weren't investigating a homicide, they were looking at an outbreak, the potential for other victims exposed to the same mislabeled product, as if.
And then there's be a recall.
Except Erin couldn't provide a clear answer. Which mushrooms, which store.
If she's responsible for these deaths by toxin, she didn't think it through. The cleverness of hiding poisonous mushrooms in nonpoisomous ones fell apart when they started asking where she got them from.
It might be a little easier to see what came apart if we remove the Beef Wellington fin the table. She picked it because it already contains mushrooms, which is ironic since that's the very reason minds went to mushroom toxicity. Anyway, had the dried mushroom powder been mixed into a dessert (wherein somehow it wasn't tasted), medical staff would not have immediately thought mushrooms or death cap, and only after the dessert was tested (if they even knew which food was the problem child), they would wonder how death caps got into the cupcakes. That she used a recipe which contains mushrooms was a good way to disguise it but also have the hospital staff the suggestion.
I truly don't think she thought they would investigate the source of the poisoning (for consumer safety, public safety or criminal charges). Mimick the symptoms, go by ambulance, get treated for nausea, upset stomach, dehydration, "pull through"...
JMO