Preheat and prep: Heat your oven to 375°F (190°C). Lightly spray a standard 12-cup muffin tin with oil, or use silicone liners for easy release.

Sauté the aromatics: Warm a skillet over medium heat. Add a small splash of oil, then the diced onion. Cook 3–4 minutes until soft and lightly golden.

Brown the beef: Add the ground beef to the skillet. Break it up with a spatula and cook until browned, about 5–7 minutes. Season with salt, pepper, garlic powder, and onion powder. Drain any excess fat if needed.

Flavor boost: Stir in ketchup, mustard, Worcestershire, and chopped pickles. Let it simmer for 1–2 minutes to meld flavors. Remove from heat and cool for a couple of minutes so it doesn’t scramble the eggs later.

Mix the binder: In a large bowl, whisk eggs, egg whites, and Greek yogurt until smooth. Fold in half of the shredded cheese.

Combine: Add the slightly cooled beef mixture to the egg-cheese mixture. Stir just until evenly combined.

Fill the cups: Divide the mixture evenly among the 12 muffin wells, about three-quarters full. Sprinkle the remaining cheese over the tops. Add a pinch of sesame seeds if you like a “burger bun” vibe.

Bake: Place in the oven and bake 15–18 minutes, until the centers are set and the tops are golden. A toothpick should come out mostly clean.

Rest and release: Let the cups cool in the pan for 5 minutes, then gently run a knife around the edges and lift them out. Cooling helps them firm up and hold their shape.

Garnish and serve: Top with extra chopped pickles, a small drizzle of ketchup or mustard, or a few shreds of lettuce and a cherry tomato half. Serve warm or at room temp.