In a large bowl, combine ground beef, seasoned salt, Worcestershire sauce and pepper. With a fork, gently stir to combine, making sure not to compress ingredients. Divide into 12 portions and shape into 2-inch patties. With thumb, gently press in the middle of each beef patty to make a small indent.
On a lightly-oiled hot grill, arrange patties in a single layer and cook for about 2 to 4 minutes. With a spatula, turn over patties and cook for another 2 to 4 minutes or until done. On the last 1 minute of cooking time, place 1 Pepper jack cheese on the top of each burger and close the grill lid to allow cheese to slightly melt.
With a knife, slice each dinner roll crosswise into halves and place cut side down on the grill to lightly toast. Spread chipotle mayo on rolls. Place patties on each bottom rolls, top with caramelized onions and cover with top rolls.