Place 4 eggs in a small saucepan and cover with cold water by 1 inch. Bring to a boil over high heat, then immediately remove from heat, cover, and let stand 10 minutes. Transfer to an ice bath for 5 minutes, then peel carefully. Set aside.

In a large bowl, combine panko and milk. Let sit 5 minutes until the breadcrumbs absorb the liquid and soften. This keeps the meatloaf tender, not dense.

To the soaked panko, add ground beef, onion, garlic, Worcestershire, thyme, 1 teaspoon salt, pepper, and the raw egg. Mix gently with your hands just until combined - overmixing makes tough meatloaf.

Press half the meat mixture into a 9x5 inch loaf pan, creating a slight trough down the center. Arrange the peeled hard-boiled eggs end-to-end in the trough. Cover with remaining meat mixture, pressing gently to seal edges and completely encase the eggs. Smooth the top.

Stir together ketchup, brown sugar, mustard, and remaining 0.25 teaspoon salt. Spread half the glaze evenly over the meatloaf. Reserve the rest for later.

Bake at 350F for 45 minutes. Remove from oven, spread with remaining glaze, and return to oven for 15-20 minutes more until the internal temperature reaches 160F and the top is caramelized. Let rest 10 minutes before slicing to reveal the eggs.