1. Preheat your oven to 375°F (190°C). Line a baking sheet with parchment paper or foil for easy cleanup—trust me, messy counters are part of the charm, but cleanup doesn’t have to be.
2. Slice the baguette lengthwise, but not all the way through—think of it like opening a book. Hollow out some of the soft bread from the inside, leaving about a 1-inch border to hold the filling.
3. Heat olive oil in a skillet over medium-high heat. Add the sliced onions and green peppers. Cook for about 5-7 minutes until softened and slightly caramelized. Sprinkle with a pinch of salt and pepper. Remove from the skillet and set aside.
4. In the same skillet, add the minced garlic and cook for about 30 seconds until fragrant. Add the thinly sliced steak, season with salt, black pepper, oregano, and crushed red pepper flakes if using. Cook for 3-4 minutes, stirring occasionally, until the steak is browned but still tender.
5. Remove the skillet from heat. Mix the cooked onions and peppers back into the skillet with the steak. Stir together gently.
6. Spread the softened butter evenly inside the hollowed-out baguette. This little step adds that rich, garlicky flavor that makes the bread irresistible.
7. Fill the baguette generously with the steak and vegetable mixture. Top with shredded provolone and mozzarella cheeses, pressing lightly to help the cheese melt into the filling.
8. Place the stuffed baguette on the prepared baking sheet. Bake for 15-20 minutes, or until the cheese is melted and bubbly, and the bread is toasted to a golden brown.
9. Remove from the oven and let it rest for 5 minutes. Sprinkle fresh chopped parsley over the top for a pop of color and a fresh note.
10. Slice into thick pieces and serve warm. Watch how fast this disappears—especially if you’ve got hungry kids like mine!

One kitchen hack I’ve picked up over the years is to slice the onions and peppers super thin. It helps them cook faster and blend better with the steak, so each bite is balanced. Also, don’t skip the resting time after baking—that cheese settles, and the bread is easier to slice.