Place the room temperature butter in a bowl then beat gently with a large spoon so it is soft, smooth, and flowing easily.
Add the garlic, Parmesan, parsley, rosemary, chili, salt, and pepper. Mix until well combined.
Layout a sheet of plastic wrap and create a line with the butter across the top. Roll the butter to create a sausage shape. Twist the ends, making the sausage smoother and more consistent.
Once the butter roll is made, chill until needed. The compound butter will firm up during this time allowing you to slice it into rounds when serving.
Lightly season the scotch steak with salt and pepper on both sides.
The first step of a reverse sear is to slowly smoke or cook on the cool side of the BBQ. Preheat your choice to 225 degrees F (107 degrees C).
Bring the Scotch steak up to a near-finished temperature, typically about 10 degrees below your target doneness. This takes about 1 hour.
Once the scotch steak reaches the target temperature, remove it from the BBQ to rest while you stoke the fire to get it as hot as possible.
When the grill is very hot, place the steak on to create the desired grill marks. As the steak is almost at the correct cook temperature there is no pressure to cook the steak so it can all be done by sight. When you have the grill marks at the desired color, turn over. Do the same for the other side. If you prefer crossed grill marks continue the process of turning the steak 90 degrees. This takes about 10 minutes.
When the scotch steak has the desired grill marks remove it from the grill to rest for about 5 minutes.
Place each scotch steak on a serving plate. Top with a slice of the compound butter; there will be enough heat left in the steak for it to slowly melt.