Place salmon skin side down into a 13 x 9 inch baking dish.
In a sauté pan, melt butter and add onions and pepper. Sauté for 15 minutes or until onions are caramelized. Remove the onions from butter and transfer into a clean sauté pan. Add balsamic vinegar and sauté for 5 minutes. Remove from heat and let cool.

After the onions have cooled, spread them over the salmon fillet and top with a thin layer of cream cheese. Sprinkle breadcrumbs over the top. Add wine to the bottom of the pan and cover with foil.
Bake in a 350 degree oven for 25 minutes. Remove foil and continue to bake for another 10-15 minutes.
Plate fish and serve immediately.

Serving Ideas: Serve with cooked spinach or kale.