Mini Macaroni and Cheese Appetizers

INGREDIENTS

1/2 lb

elbow macaroni

1 1/2 tbsp

unsalted butter, plus more for brushing

1/4 cup

freshly grated Parmesan- Reggiano cheese

2 tbsp

all-purpose flour

3/4 cup

milk

4 oz

cheddar cheese, shredded (1 packed cup)

4 oz

deli-sliced American cheese, chopped

large egg yolk

1/4 tsp

smoked Spanish paprika