Another answer -

You are a

Burger :)

Explanation

Layer 1 - Cheese with rough edges
Layer 2 - Fillings/Toppings. Often it's difficult to know what stuff's are included in a burger. They keep changing according to what kind of burger you are eating.
Layer 3 & 4 - Bun which serves same purpose

Here's an example -

Another answer -

You are a

Burger :)

Explanation

Layer 1 - Cheese with rough edges
Layer 2 - Fillings/Toppings. Often it's difficult to know what stuff's are included in a burger. They keep changing according to what kind of burger you are eating.
Layer 3 & 4 - Bun which serves same purpose

Here's an example -