Heat the oven to 400°F
Stir the green beans, soup, milk, 1 cup cheese and ⅔ cup French fried onions in a large bowl
Lightly grease two 24-cup (1 ¾-inch) mini muffin pans
Unfold one pastry sheet on a lightly floured surface
Roll the pastry sheet into a 10x12-inch rectangle
With the long side of the pastry sheet facing you, use a sharp knife to cut the pastry sheet lengthwise into six 2-inch strips
Then cut the pastry sheet crosswise into four 2 ½-inch strips
This will create 24 (2-inch x 2 ½-inch) pastry rectangles
Press the rectangles into the mini-muffin pan cups
Repeat with remaining pastry sheet to make 48 rectangles
Fill each muffin cup with about 1 tablespoon green bean mixture
Bake for 15 minutes
Meanwhile, stir the remaining ½ cup of cheese and ⅔ cup of onions in a small bowl
Remove the muffin pan from the oven
Top each mini green bean casserole with 1 teaspoon topping mixture
Bake for an additional 5 minutes or until golden brown
Let stand 5 minutes before removing the minis from the muffin pan
