British Pub Burger Recipe! (Cottage Pie Burger)

Pub Grub Baby! Tried to take one of my favorite British comfort foods (Cottage Pie) and turn it into a burger. I was pretty darn happy!
“Sauce” ingredients:
1 carrot peeled and finely diced
1 celery stalk, peeled and finely diced
1/2 medium onion finely diced
1.5 cups unsalted beef broth
2 tbs tomato paste
2 tbs unsalted butter
About 1-2 tbs flour
1-2 splashes Worcestershire Sauce
Salt and pepper to taste.
Mushy Pea Mayo:
1 cup mayo
1/4 cup cooked and cooled peas
Blend em!
Ballistic Griddle:
Ring Cutter (For forming patties)