Preheat the oven to 400°F. Coat a large baking sheet with cooking spray.
Combine 5 tablespoons of the dressing, beef, egg, breadcrumbs, salt and pepper in a bowl. With lightly dampened hands, form the mixture into 8 balls. Flatten each slightly and place on the prepared baking sheet.
Bake the meatballs until lightly browned and cooked through, 20 minutes.
Assemble the sliders with tomato slices, arugula and meatballs. Drizzle the meatballs with the remaining 3 tablespoons Hidden Valley® Greek Yogurt Ranch Dressing.
For safe meat preparation, reference the USDA website.