Preheat the oven to 100C. In a large bowl, mix the first 12 ingredients together for the patties and season with salt and pepper to taste.
Roll into golf-ball-sized balls and place on a tray lined with baking paper. Place in the fridge until ready to cook.
Heat the oil in a large fry pan over a medium heat. Add the meatballs in batches, pushing down into a patty shape about 1.5 cm thick. Fry the patties for 5 minutes on each side or until cooked through. Place cooked patties in the oven until all of the patties are cooked.
To make the sauce, in a saucepan over a medium heat, melt the butter and add the onion. Season and cook for 5 minutes or until softened.
Add garlic and cook for a further 2 minutes. Add the cream cheese and blue cheese and cook until both are melted. Add the cream and cook for a further 5 minutes over a low heat. Season to taste.
To make the crispy onions, soak the onion rings in milk for 20 minutes. Drain and toss in garlic powder and paprika.
In a deep saucepan, heat the oil to 175C and deep-fry the onions until golden and crispy. Remove and drain on paper towels. Season.
Slice the slider buns in half and lightly toast. Place a patty, a spoonful of the sauce and some crispy onions on to each bun. Top each with a cornichon skewered with a toothpick.
More classic American recipes from Karena and Kasey