In a large mixing bowl, combine the ground beef, ground pork, beaten eggs, grated onion, minced garlic, Worcestershire sauce, ketchup, kosher salt, black pepper, smoked paprika, dried thyme, dry mustard powder, and the panade paste. Using your hands, mix until the ingredients just disappear into a uniform mass — stop the moment it is homogeneous. Overworking develops myosin cross-links before cooking and produces a rubbery, dense loaf. Work fast; warm hands smear the fat phase.
1 lb 80/20 ground beef chuck, 1 lb ground pork shoulder, 2 large eggs, 1/2 cup yellow onion, 3 cloves garlic, 2 tbsp Worcestershire sauce, 2 tbsp ketchup, 1 tsp kosher salt, 1 tsp black pepper, 1 tsp smoked paprika, 1/2 tsp dried thyme, 1/2 tsp dry mustard powder, 1/3 cup whole milk