He hated it.
The whole experience was a lot of fun. Turns out while Benny loves bananas, he didn't much care for the combination of ice cream and fruit. He did, however, very much enjoy the hot fudge – and the extra M&Ms his sister gave him from her sundae. Blue only, you'll notice.
Blood sugar before the ice cream and lunch was 190 (a little higher than I expected). We assumed about 50 carbs for the sundae and dosed him for it. BG went to about 210 and stayed there for a few hours. Got him back down to normal just before dinner.
I'm considering it good practice for the next couple of days – Thanksgiving is here and so are my brothers-in-law. That means outrageous food (my brother-in-law David makes his own marshmallows!) but also lots of good times. I'm so thankful for the diabetes tools we have now that don't make the two mutually exclusive.
Bring on the (carefully-measured and insulin-dosed for) holiday feast!