Beefy Grilled Cheese Recipe

Prepare and cook bacon

Heat a large skillet over medium heat. Add bacon slices in a single layer and cook 3–5 minutes per side until crisp or to your liking. Transfer cooked bacon to a paper towel-lined plate to drain. When cool, roughly chop or leave whole depending on sandwich size.

Season and cook steak

While bacon cooks, pat the steak slices dry. In a bowl toss steak with 1 tbs olive oil, 1 tsp kosher salt, 1 tsp black pepper, and 1/2 tsp garlic powder. After removing bacon (reserve ~1 tbs bacon fat in skillet if present), heat the same skillet over medium-high heat. Add the seasoned steak slices in a single layer (work in batches if necessary) and sear 1–2 minutes per side until browned and just cooked through (medium-rare to medium). Remove steak to a plate and let rest 3 minutes, then thinly slice against the grain if not already thin.

In a medium sauté pan, melt 2 tbs unsalted butter over medium heat. Add the thinly sliced onion and stir to coat. Season with 1/4 tsp salt, 1/4 tsp black pepper, and 1/2 tsp brown sugar. Cook, stirring occasionally, for 12–15 minutes until the onions are soft and beginning to caramelize. If onions start to stick or brown too quickly, lower the heat and add a splash of water. Stir in 1 tsp balsamic vinegar (optional) at the end and cook 30 seconds more. Remove from heat.

Preheat a clean large skillet or griddle over medium-low heat (it should be hot enough to melt cheese slowly without burning bread).

Butter one side of each slice of sourdough with the softened butter (4 tbs covers 8 slices lightly). If using, spread Dijon mustard thinly on the unbuttered side of 4 slices to add brightness.

Layer the sandwiches on the unbuttered sides: start with a sprinkle of mixed cheeses (about 2 tbs cheddar + 1.5 tbs Swiss + 1.5 tbs mozzarella per sandwich), then place a portion of sliced steak (about 2.5 oz per sandwich), 1–2 strips of chopped or whole bacon, and a generous spoonful of the sautéed onions. Top with another light layer of cheese to help the top slice stick. Close sandwiches with the buttered side out.

Place assembled sandwiches in the preheated skillet. Cook 3–4 minutes per side over medium-low heat, pressing gently with a spatula, until bread is golden brown and cheese is melted. If bread is browning too fast before cheese melts, lower heat and cover the pan for 1–2 minutes to trap heat and help melting.

Transfer sandwiches to a cutting board and let rest 1 minute, then cut each in half. Garnish with chopped parsley if desired and serve hot.