Putting peanut butter on bread is a physical change.
When you put peanut butter on bread there are no new chemical bonds being formed when you spread the peanut butter.
So it's a physical change and not a chemical change when you spread peanut butter on bread.
Physical changes involve a change in state or the appearance without creating a new substance.
Examples of physical changes include mixing ingredients, cutting bread or changing the temperature of something such as a substance.
Chemical changes on the other hand involve formation of new substances with different chemical properties.
Examples of chemical changes are burning wood, rusting metal or baking bread.
When you spread peanut butter on bread, crackers or other foods you only change the appearance of the bread, crackers or other food by adding the peanut butter.
You're not creating any new chemical compound.
The peanut butter remains the same substance, but it's physical state is changed as it is spread onto a surface.