In a medium bowl, combine 0.5 lb ground Angus beef, 2 tbsp fine dry breadcrumbs, 1 egg yolk, 1 tsp Worcestershire sauce, 3 tsp kosher salt, and 0.5 tsp freshly ground black pepper. Mix gently with your hands or a fork until just combined — avoid overworking so patties remain tender.

Form patties with pocket

Divide the mixture into two equal portions. On a lightly oiled surface, flatten each portion into a 4-inch disk about 1/2 inch thick. Make a shallow well or pocket in the center of each disk with your thumb, keeping the outer edges slightly higher to form a sealed rim. This creates space for the stuffing.

Stuffing (choose one per patty)

Cheddar & Bacon option

If using cheddar & bacon: mix 2 tbsp melted sharp cheddar with 2 tbsp crumbled cooked bacon and 1 tbsp softened cream cheese (optional) in a small bowl until smooth. Spoon roughly 1.5 tbsp of the mixture into the pocket of each patty. Fold the edges of the beef up and over the filling, pinching and pressing seams to fully enclose the filling and reseal into a patty shape about 3/4 inch thick. Ensure there are no gaps.

Quahog (clam) option

If using clam stuffing: combine 2 tbsp chopped drained clams with 0.5 tsp minced garlic and 1 tbsp softened cream cheese (optional) to bind. Spoon about 1.5 tbsp into the patty pocket and seal the beef around it the same way, pressing firmly to prevent leaks.

Cooking

Preheat a cast-iron skillet or heavy frying pan over medium-high heat. Add 1 tbsp olive oil and let it shimmer but not smoke. When hot, carefully place the sealed patties seam-side down first to sear and seal the closure for 1 to 1.5 minutes. Flip and sear the other side for 1 minute.

Reduce heat to medium and continue to cook, flipping once more if needed, until internal temperature reaches 160°F (71°C) for medium-well (about 4–6 more minutes total depending on thickness). If you prefer slightly less done, cook to at least 160°F for food safety with clam stuffing; for plain beef with cheese, 160°F is still recommended to ensure a safe internal temperature when using mixed fillings. If the cheese oozes out, scrap pan bits into the burger when assembling.

During the last 1 minute of cooking, butter 1 tsp unsalted butter and toast the inside faces of the bun in the same pan until golden, about 30–60 seconds.

Assembly & Toppings

Spread 1 tbsp mayonnaise on the bottom bun and 1 tsp mustard on the top bun (or your choice of condiment).

Place 1 leaf lettuce on the bottom bun, then add the cooked stuffed patty. Top with 2 slices tomato and 3 rings red onion. Add pickles if desired.

Close the burger, press gently, cut in half if serving two, and serve immediately while hot.