Upgrading to 32GB RAM for Mac mini Server (MD389LL/A) I'm using a Mac mini Server (Late 2012) with 2,3 GHz Intel Core i7 processor and 16GB RAM. This type of processor (Intel® Core™ i7-3615QM) supports a max memory size of 32GB. Look at specification: Here.

Is it possible to upgrade RAM in my Mac mini to 32GB (for instance a Crucial Kit 2x16GB)?

I understand that Apple has to update Memory Reference Code in the firmware of the Mac mini but maybe exists another way to upgrade a memory.
No. That Mac mini is limited to 16 GB max ram. 

You can be pretty sure that if it's not mentioned in Everymac or sold by OWC[MacSales] or ramjet.com, it can't be done. These reputable sellers will always provide good research and advice if more memory can be used past Apple official specifications. 

Whether you would choose them as your vendor or not, they tend to cover all possibilities &amp; often support things that Apple never intended.