Preheat the oven to 425 degrees , and line a baking sheet with parchment paper.

Slice the jalapeños in half lengthwise and carefully scoop out the seeds and white parts with a small spoon. Discard seeds/white bitter parts, and rinse jalapeños to remove all seeds. Arrange on the parchment lined sheet, cut side up.

In a medium nonstick frying pan, heat the olive oil over medium heat. Add diced onions and season with salt and pepper, cook stirring occasionally for 5-7 minutes until softened, remove from pan to a bowl and set aside.

Add steak to the pan, and season with salt and pepper. Cook, stirring and breaking up the meat occasionally- until browned and cooked through, 4-5 minutes. Turn off the heat, remove to a cutting board and chop into finer, biter sized pieces, if needed.

Add the warm steak to the bowl with the chopped American cheese and cooked onions (and hot sauce, if using), and toss well until a paste-like mixture forms (for best results, do this while the steak is still warm so it fully incorporates).

Stuff each prepared jalapeño pepper with the mixture, mounding over the top.

Bake the stuffed jalapeños in preheated oven for 15-20 minutes, until topping is browned and bubbly and peppers are tender.

Allow to cool 5-10 minutes before serving.