Preheat your oven to 375°F.
Blanch the green beans by boiling them in salted water for about 3 minutes, then drain and set aside.
Cook bacon in a skillet over medium heat until crispy.
Remove from the pan and crumble it once it cools down.
Reserve a bit of the bacon grease in the skillet.
Add the cream of mushroom soup, cheddar cheese, chicken broth, cayenne pepper, salt, and pepper to the reserved bacon grease.
Stir everything together until the cheese melts.
Mix the cooked green beans and pimientos into the cheese sauce.
Pour everything into a casserole dish.
In a small pan, heat olive oil and stir in the panko breadcrumbs until they are golden brown.
Sprinkle these breadcrumbs over the green bean mixture.
Bake the casserole in the preheated oven for about 30 minutes or until the top is bubbly and golden.