Melt butter in a large skillet over medium heat until it's melted and just beginning to bubble (make sure not to let it burn).

Add onions and cook, stirring occasionally, until onions are soft, medium brown in color, and slightly burnt (30 to 40 minutes). The technique is just like caramelizing, but you take it a step or two further. The goal is a darker brown color and nice little burnt bits—but don't go too far.

When onions are done, add eggs, walnuts, and salt. Chop and mix well. Pop the mixture into a food processor if you want a more realistic chopped-liver texture, pulsing until smooth. I usually leave a few chunks unprocessed, as shown in the photo above. (Sometimes I just skip the food processing step altogether.)

This dish is delicious served warm, but room temperature is good too.