I cashed in some savings bonds on December 2015 with Chase Bank. I am trying to figure out how to report this, but Chase has not sent me any forms or documentation.

You need to get the 1099-INT form from Chase.

(Note:  I suspect this is an old post from the 2015 tax season in Jan-April of 2016).

In the 2015 software, Create your own 1099-INT form as coming from the "US Treasury"

Put the interest received on the bonds in box 3 of that 1099-INT.

1) if they were all EE bonds.   Subtract half the face value from the total proceeds....that is the interest received.

2)  If they were all I-bonds.   Subtract the face value from the total proceeds...that is the interest received.

3)  If they were a mix of I- and EE-bonds....you've got a problem if you haven't kept detailed track your self....talk to someone at the Chase branch you dealt with.  Maybe they send the 1099-INT to the wrong address, and you can get a copy there.....if at a branch you are no longer close to...find any Chase branch and talk to the staff there. They may have computer access to those details.