Are you doing a B2B or spending any time in ARN? If the latter, you should go into town to Svedjan Bageri and get yourself a coffee and a cardamom bun. It’s better than any food you’d get on board or in the airport.

Alternatively, if you’re just connecting, ARN has decent pastries and nice sandwiches at RC in Terminal 5 where BA flew from when I was there last summer.