
Trying to answer the eternal question, if you use pancakes instead of bread, is it still considered a Sandwich? Leaving the fact that it's weird out of the equation, there are some people who actually enjoy making themselves a Pancake Burger. However, we want to know if it can be called a "sandwich".
It seems like the answer is fairly obvious, but we decided to examine this issue further. Before we continue, let's review our previous definition of a sandwich.
Definition of a Sandwich
A Sandwich is an item of food consisting of two pieces of bread with a filling between them, eaten as a light meal.3
Well, that seems pretty clear, the outer sides of the sandwich must be pieces of bread. So, the question is whether a Pancake is part of the Bread family. We Googled some more and the results are below.
Pancakes are Part of the Bread Family
Pancakes are part of the original group of flat, quick-breads. For thousands of years people made flat ground wheat, nut or non-wheat cakes without leavening. The origin of the American pancakes and waffles can be traced back to 17th century Dutch settlers, and were called pannekoeken and stroopwafels. So popular in Colonial days, pancakes were often flavored with pumpkin or spices and, waffles were popular at holidays.1
Pancakes and waffles are bread, the type known as ‘quick breads’ - bread leavened with baking soda or baking powder. Waffles are almost identical to pancakes, only having a little more fat in the batter, and cooked on a grid shaped pan (waffle maker). So, pancakes and waffles are bread (being quick breads), and they are cooked on a griddle or pan (as are flat breads such as tortillas).2
Answer to the Question
YES, a pancake burger can be considered a Sandwich. Since pancakes are considered "quick breads", then it can be used in place of traditional breads.

References
1. Crafty Baking (https://www.craftybaking.com/learn/baked-goods/quick-breads/types/pancakes-and-waffles)
2. Quora (https://www.quora.com/Are-pancakes-and-waffles-considered-bread)
3. Oxford (2020) https://www.lexico.com/en/definition/sandwich