I made it with kale last night and it was not bitter at all. In fact, I think spinach would be more bitter. I cut out the ribs & stems before I coarsely chopped it. I used turkey sausage and added a bit of red pepper flakes since I couldn't get spicy turkey sausage this time. I did add a splash of half & half at the end (maybe 1/4 cup) and this added a little richness. It was delicious! Had it for lunch today and it was equally good.