She’s so pretty! I would describe her as a blue and white bicolor (in the mitted tuxedo pattern) Domestic Longhair. I agree with Mightyboosh that Norwegian Forest Cat is probably the closest breed lookalike.
I would describe her as a blue and white domestic longhair. Very pretty!
You asked what breed she might be mixed with. Unlike dogs, most cats are simply domestic cats without specific breed ancestry, not mixes of breeds. Your pretty girl doesn't have obvious features that would tell us that she has ancestors of any specific breed. Comparing her to a "lookalike breed" is just for fun and doesn't really tell you anything about her ancestry.