Preheat oven to 350 degrees F.
Cook bacon in medium dutch oven over medium heat until browned and crisped. Transfer bacon to a paper towel lined plate then discard all but 2 Tablespoons of bacon drippings.
Saute onions in remaining bacon drippings until softened, about 5 minutes.
Stir in garlic and cook for a minute. Reduce heat to low.
Boil green beans in pot for 5 minutes, until just fork tender.
Add beans to onions and garlic along with the crisped bacon.
To make sauce melt butter in a medium saucepan over medium heat.
Whisk in flour, salt and pepper until well combined then whisk in chicken broth until thick and creamy, for about 3-4 minutes.
Once hot and creamy add shredded cheese until melted.
Pour cheese sauce over beans then transfer to a 9 inch pie plate.
Trim square puff pastry edges to more of a round. Lay puff pastry over beans, folding edges under. Cut 4-5 slits to allow for steam to escape.
Bake for 35-40 minutes or until puff pastry is nice and golden.
Let cool for 15 minutes before slicing into.
Enjoy!!