Preheat oven to 400°F (200°C). Line a baking sheet with aluminum foil and spray with cooking spray; set aside.

In a large bowl, combine the ground beef, egg, milk, bread crumbs, diced onions, salt, and pepper. Stir until just combined, being careful not to overmix.

Using a 2-tablespoon cookie scoop (or your hands), form approximately 18 to 20 meatballs. Roll them into smooth balls and place them on the prepared baking sheet, spaced about 1-inch apart.

Bake for 17 to 20 minutes, or until the centers of the meatballs are no longer pink and are cooked through. Set aside.

In a large skillet, melt the unsalted butter over medium heat.

Add the minced garlic to the skillet and sauté for about 1 minute, stirring frequently, until fragrant and tender.

Stir in the ketchup, honey, and low-sodium soy sauce. Mix well to combine.

Add the baked meatballs to the skillet with the sauce. Toss and stir gently to coat them evenly. Simmer over low heat for 3 to 5 minutes, or until the sauce has thickened slightly and the meatballs are well coated. Stir intermittently.

Transfer the meatballs to a serving platter or bowl. Insert a toothpick into each meatball if desired for easy serving, and enjoy!