Preheat oven to 450°F. Mix 1/2 cup broth and oats in medium bowl. Let stand 5 minutes. Mix in meat, onion, egg, dill, mustard, salt, and pepper. Transfer mixture to rimmed baking sheet; shape into two 3x6-inch rectangular loaves.

Bake meat loaves until browned and cooked through and thermometer inserted into center registers 160°F, about 25 minutes. Using large spatula, transfer loaves to platter. Place baking sheet directly atop 2 burners. Add remaining 1/2 cup broth to sheet. Boil pan juices over high heat until reduced by half, scraping up browned bits, about 2 minutes. Pour sauce over loaves and serve.