Hi Summer!
What a great question in submitting all we do to God's will for us! I see that others have already given you some great answers, but I'd like to add a couple of stories.
My Mom is very health-conscious and tried very hard to raise us with very few fried foods or sugary treats. For whatever reason, it worked for some family members -- their idea of a "yummy snack" is, literally, a head of lettuce (they eat it like others would an apple.)
Unfortunately, it didn't work for me, and I pretty much went in the exact opposite direction. Once I had a job and could pay for some of my own food, my lunch of choice would be two candy bars -- every day. The problem for me is that it started to take over other areas of my life -- I was soon tempted to skip dinner so that I could have another form of dessert, or would be trying to obsessively calculate how long I had to exercise to try to burn off all the sugar. I was spending more than I should have been on junk food, and tried to cut calories on healthy foods so I could eat more things I liked, but were completely unhealthy.
In my case, "a daily candy bar habit" was most definitely a sin (and is something I still struggle with today.)
However, in your case, I believe you mentioned getting over an illness and this is the one thing that actually sounds appetizing.
This reminded me of a story I'd seen about a girl who was recovering from anorexia. She said that treatment centers had been worthless to her because the minute she saw a plate of food waiting for her, it brought out her urge to fight anyone who tried to make her eat.
Instead, her family came up with a different kind of recovery plan for her at home. Meals were always with other family members, and were served buffet-style so that EVERYONE, not just her, started out with an empty plate, so she was given the CHOICE of what she put on it and what/how much she ate -- just like everyone else was doing, so she wasn't singled out or coerced.
At every meal they had, her mom made sure it included some kind of sweet treat to the girl's liking -- usually in the form of a brownie, which was deemed her "safety dessert." The girl liked desserts enough that even if she chose not to eat anything else, she would almost always choose to eat this one safety food, and might be her only chosen source of calories for the day.
In this case, "a daily brownie" habit was her literal lifeline to recovery, as she gradually relearned how to feed herself in a healthier way.
From what you described, it sounds like your daily ice cream habit might very well be a connection for you towards a healthy recovery.
Take it to God -- and if you feel at peace and don't have any convictions about it, I say raise your spoon in thanks and dig right in.
Hope this helps... Please keep us posted on how you're doing.