Preheat oven to 400 degrees. Line a large rectangular sheet pan with parchment paper.
In a large skillet over medium high heat break up ground beef and cook until no longer pink. Season with 1/4 tsp salt and 1/4 tsp black pepper. Stir in A1 steak sauce. Turn off heat and remove cooked meat to a medium bowl and set aside.
In the same skillet over medium high heat, melt 4 TBS butter. Add in sliced onions, 1/8 tsp salt, and 1/8 tsp black pepper. Cook for 8 minutes, stirring occasionally, until softened and slightly browned. Turn off heat.
Roll out pizza dough on parchment lined sheet pan. Spread Thousand Island dressing all over pizza dough to the edges. Sprinkle with 1 cup of shredded cheddar cheese.
Place cooked meat mixture all over the cheese evenly. Place softened onions all over the meat mixture. Top with remainder shredded cheese evenly.
Bake in preheated oven for 18-20 minutes until cheese is melted and crust is golden brown and cooked through.
Cut into squares and serve with additional Thousand Island dressing, if desired.