A brownie is a flat, baked dessert square that was developed in the United States at the end of the 19th century.
It was popularized in the U.S. and Canada during the first half of the 20th century.
It is a cross between a cake and a soft cookie in texture and comes in a variety of forms.
Depending on its density, it may be either fudgy or cakey and may include chocolate chips, nuts, or other ingredients.
A variation made with brown sugar and chocolate bits but without melted chocolate. (source)
So can hamsters eat brownies?
If they nibble a few small pieces they will be fine, but they are not the best food for them to eat as they are too sweet for them.