Found a version of this recipe elsewhere, and have made it several times, tweaking it each time. Finally have it the way I like it. And, the last time I made it, I made an easy mushroom gravy for it, and served mashed potatoes and green beans.
Preheat oven to 350º F. Spray a 9x5-inch loaf pan with cooking spray.
Sweat onions and garlic in vegetable oil until onions are transparent. Set aside to cool for handling.
Beat the eggs in a large mixing bowl until smooth., then whisk in 1/3 cup barbecue sauce, chipotle chilies, adobo sauce, tomato paste, kosher salt, black pepper, celery salt, cumin and worcestershire sauce until evenly smooth.
Mix in the onion, oatmeal and ground beef with your hands until evenly blended. Pack the mixture into the prepared pan. Brush the top of the meatloaf with 2 more tablespoons of barbecue sauce.
Bake in the preheated oven until no longer pink in the center, about 1 hour. An instant-read thermometer inserted into the center should read at least 160º F.