It really shouldn't be at the point it is TBH .... explaining your place has more room and will be more comfortable should have been enough for her to agree to cook at your place
If it isn't understandable ... then she's more interested in what she wants as opposed to how much nicer it would be for almost everyone else
It's pretty immature and petty to be so adamant about "cooking" and "entertaining" in a place that may end up being over crowded ... isn't the whole idea supposed to be spending time with everyone and
everyone enjoying it .. making nice memories ? It's not supposed to be about how much of an impression you can make on people ... that's egotistical and self-centered ... people should like you for who you are .. not what you can do or how well you can do it
If she already knows you'd prefer it at your house then it should be a no brainer and she should have asked you to help her get all the stuff she needs to cook with taken over there ... it's not even a sacrifice .. it's merely one small concession to make YOU happy ..

I don't get why she doesn't want to do that for you .. especially for Christmas
