In small skillet, melt two tablespoons butter and toss in onions. Cook on low heat occasionally stirring until onions are a deep dark color. Go slow; good caramelized onions can take thirty minutes. Set aside.
Melt remaining butter in a small sauce pan over low heat. Allow butter to start to foam and turn brown. Keep a close eye on it as to not burn the butter. Once browned, remove from heat.
Stir in honey and red pepper flakes into browned butter.
Pour brown butter over cooked ravioli. Top with caramelized onions and chopped fresh sage. Spritz with lemon juice.
