Heat 2 tbsp. butter in 12” non-stick skillet over medium high heat. Add onions. Cook, stirring occasionally, until soft and translucent, about 5 minutes. Add eggs to pan. Cook, stirring with spatula, until just set, about 1 minute. Stir remaining butter until melted. Add manioc flour and Adobo. Cook, stirring often, until flour is crisp and golden brown, about 10 minutes. Stir in parsley.
Transfer to serving bowl; top with olives and egg slices. Serve hot or at room temperature.
Serve with Feijoada.