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: https://www.cast-iron-grate.com/ballisticgriddle.html
Ring Cutter (For forming patties) https://www.amazon.com/gp/product/B0061UKLKC/ref=as_li_tl?ie=UTF8&camp=1789&creative=9325&creativeASIN=B0061UKLKC&linkCode=as2&tag=babb0f-20&linkId=64dce14f8bc98d87b54478d0b7e8263d