Caramelized Onion & Bleu Cheese Burgers

I found the recipe for this delicious burger on The Pioneer Woman Cooks and slightly adapted it for us. It's a nice change from your ordinary cheeseburger!

Caramelized Onion & Bleu Cheese Burgers
1 lb. ground turkey (or beef)
salt & pepper
Tabasco sauce
2 tb. butter
1 onion, thinly sliced (she uses red, I used white b/c that's what I had)
2 tb. brown sugar
1/2 c. bleu cheese, crumbled
mayonnaise
4 hearty, crusty buns (no pansy soft ones!)
Fresh salad greens

First, melt butter in a skillet. Stir onions and brown sugar in, saute on low heat for about 15 minutes, until soft and caramelized. Next, mix your meat with 1 tsp. salt, 1/2 tsp. black pepper, and a few shakes of Tabasco. Form into 4 patties (Pioneer Woman makes one huge burger, but that's a bit much for me, so I made 4 normal-sized ones). Grill or fry in skillet on both sides for several minutes, until no longer pink in center. Meanwhile, brush some more butter on a skillet and brown cut sides of buns for a few minutes. Mix about 1/2 c. mayo with a few shakes Tabasco, spread thinly on both sides of buns. Top burgers with a pile of onions and a sprinkle of bleu cheese. Place on bottom bun, top with greens and top bun, and enjoy!