Season steak with salt and pepper. Let it rest on the counter for about 30 minutes before cooking.

While the steak is resting, caramelize the onions. In a large non-stick skillet over medium-low heat, melt 2 tablespoons butter. Once melted, add the onions and sauté them for 25-30 minutes, stirring occasionally, until they are very tender and caramelized to a rich golden brown color. Transfer to a plate and set aside.

Preheat oven to 350°F. Spray a 9x13-inch baking dish with nonstick cooking spray. Set aside.

In the same skillet over medium-high heat, melt the remaining butter. Add steak and cook for 4-5 minutes on each side, or until meat is cooked to your liking.

Carefully tip up the skillet, spooning the butter back over the steak. You can also add more butter to the pan if you want.

Set the steak aside to cool slightly, approximately 5 minutes.

Slice the steak against the grain as thinly as possible.

Split your rolls in half horizontally and place the bottom halves into the prepared baking dish.

Evenly pour about ¼ cup of the melted cowboy butter over the bottom halves of the rolls in the pan.

Top with the steak slices.

Evenly place the jalapeños and shredded cheese over the steak.

Evenly distribute the caramelized onions over the cheese.

Place the top halves of the rolls on top of the onions. Brush the tops of the rolls with about ¼ cup melted cowboy butter.

Cover the dish with aluminum foil and bake for 15 minutes, or until the cheese is hot and bubbly.

Remove the foil and bake for an additional 3-5 minutes (or until the tops of the sliders turn a golden brown).

Remove from oven. Brush the remaining melted cowboy butter over the warm sliders.

Slice and serve.