butter- softened or cold in tartines lemon creme?

I made it using cold, but not icy cold butter and it came out great. What a keeper! But, I used a one piece encapsulated double boiler because I couldn't find a ssl bowl that was shallow enough and it would not come up to 180 degrees.

thanks sooo very much! perfect timing as well

I've done it successfully with both! Probably best for it to not be icy cold -- that could cool the curd down too quickly and you could be left with small unincorporated bits of butter.