Making a rare custom cold biome

Hi,

i have a problem with creating a custom biom,

I want to make a hot spring biome for my mod but i tried every setting and i can't get it right.

i want the biom to be rare and small (around 6x6 chunks),

i it needs to spawn around cold bioms (snowy plains).

The tarrain should be a more hilly plains,

and i don't want it to spawn underground with was a acuring problem

Could someone give me the biom settings or tell me how thay work to achieve whis result?

also, im using the forge 1.20.1 generator if that helps.