Pumpernickel Onion Toasties are a classic appetizer with 4 ingredients that take 15 minutes to make. Be ready for Surprise Company with this perfect little treat.
Place bread on baking sheet or broiler pan. Add one slice of onion to each piece of bread.
Mix Mayo and Parmesan cheese together. Dot each toastie with about 1 teaspoon of the mixture. Spread it out carefully using an offset spatula or butter knife.
Cook until brown and bubbly, about 8 to 10 minutes.