Place 3 Tablespoons of dehydrated onion flakes in a small bowl and cover with boiling water. Set aside.
Prepare the dressing by mixing all ingredients except milk in a small bowl. Microwave 25 seconds, stir well and refrigerate. Once cool, add in milk until desired consistency is reached.
Brown ground beef with onion powder until fully cooked. Drain any fat and set aside.
Divide the lettuce into quarters and top with cheese, beef, tomatoes, pickles, and onion. Top with the dressing and sprinkle with 1 Tablespoon of onion flakes, serve immediately.
Notes
Prep salad in advance and refrigerate up to 3 days! Make ground beef ahead of time, refrigerate separately from salad ingredients.
Refrigerate leftover dressing in a jar with a tight-fitting lid for up to 5 days. Keep leftover cheeseburger salad in the refrigerator and in an airtight container.
Add fresh lettuce and cheddar cheese to refresh the salad before serving.