Source: Vintage Recipes from Amy Vanderbilt's Complete Cookbook (c. 1961)
grated Parmesan cheese
onin, peeled and chopped
tiny rounds of bread cut with 1-inch cookie cutter
1 - Mix mayonnaise and cheese to consistency of softened butter.
2 - Place little choope onion in the center of each round of bread.
3 - Cover with mayonnasise cheese mixture.
4 - Put under broiler until puffed and brown.
5 - Serve immediately.