Hmmm.
I love Amsterdam at 7:00 am on Sunday mornings since I'm the only one on the streets and I feel like I own one of the greatest cities in the world!
Unfortunately, pretty much everything is closed on Sunday mornings.
Dutch pancakes are great for breakfast, brunch, lunch, snacks, dinner, late meals, etc.!
Personally, I would have brunch at The Pancake Bakery (Prinsengracht 191) which opens at 11:00. It's located about 3 blocks North of the Anne Frank House and is about 1 km from Centraal (where you meet up at 1:00).
www.pancake.nl/indexeng.php
While the food is great there, the service is slow and indifferent. So getting there at 11:00 ensures a timely departure for the 1:00....