I'm planning to experiment with this for three days next week. Here's the menu I've worked up with 88% fat. I plan to do the same thing all three days.

Breakfast:
Coffee with 4 tbsp heavy cream
1 egg scrambled with 1 tbsp butter

Lunch:
1 egg scrambled with 1 tbsp butter

Dinner:
2 eggs scrambled with 1 tbsp butter

Snacks (2):
20 spanish olives each snack

(My Fitness Pal app says 20 olives is 100 calories and no carbs or protein.)

If you're interested, I'll let you know the result of the experiment.