The pattern is “Weinrote Raffinesse” from the magazine “Fantastische Strickideen Style Edition”, 05/2014. I think this is a copy of a pattern from Simply Knitting, but the designer’s name is not mentioned, and I can’t find the original.
I worked with both yarns held together throughout on 4.0 mm needles although the patterns calls for 5.0/5.5 mm needles. This is why I made size L/XL to fit my S/M frame.
The shape is not perfect, the collar being so wide that the cardigan will easily slip from the shoulders when it’s not fastened somehow. Maybe I’ll add a stabilizing seam at the back of the collar.