Green Bean Casserole

Name: Green Bean Casserole
Ingredients: 2 lb. fresh green beans, ends cut off; 4 slices bacon, cut into 1/4-inch pieces; 1/2 large onion, chopped; 3 cloves garlic, minced; 4 tbsp. butter; 4 tbsp. all-purpose flour; 2 1/2 c. whole milk; 1/2 c. half-and-half; 1 1/2 tsp. salt, plus more to taste; Freshly ground black pepper, to taste; 1/8 tsp. cayenne pepper; 1 c. grated sharp cheddar cheese; Chicken broth, if needed for thinning; 1 (4 oz.) jar sliced pimientos, drained; 1 c. panko breadcrumbs