Step 1: Heat oven to 350 degrees F. Set aside a baking sheet.
Step 2: In a large bowl, mix together the ground beef. Lipton onion soup mix, peanut butter, and milk.
Step 3: Spread the meat mixture on the baking sheet. Use a rolling pin to roll over the meat to smooth it out. Bake for about 10 minutes. The meat will shrink. Put the diced onion all around the edges.
Step 4: Bake another 7-10 minutes, until the cheese is melted.
Step 5: Add the tops of the rolls (the bottom part of the rolls will just sit on the counter.) Bake for about 5 more minutes.
Step 6: Remove from oven. Slice the meat into individual sliders with a pizza cutter. Pick up the slider meat and its top bun with a spatula and set it on the bottom bun.