Preheat oven to 400 degrees. Place bacon on a large baking sheet. Bake in the oven until crisp, about 12-15 minutes.
Place buns on another large baking sheet and brush with egg wash. Sprinkle everything seasoning on top. Bake on a different rack in the oven until lightly toasted, 5-6 minutes.
Cut chicken breasts in half vertically, then cut each piece lengthwise or horizontally so you have four thin portions of chicken from each breast, 8 total. They should be about the size of the slider bun. Season chicken on both sides with salt and pepper.
Mix garlic powder, onion powder, paprika and oregano together in a small bowl. Sprinkle chicken on both sides with spice mixture.
Heat a large non-stick skillet to a medium-high heat. Add 3 teaspoons olive oil. Sear chicken on both sides until cooked through, about 3 minutes per side.
While chicken cooks, heat a medium saucepan to a medium heat. Add remaining teaspoon of olive oil, Once oil is hot, add onion and remaining salt. Saute until slightly softened, about 2-3 minutes. Add garlic, saute another minute. Add spinach, artichokes, cream cheese, sour cream, mayo, parmesan and nutmeg. Reduce the heat to low and heat until both the cream cheese and parmesan cheese is melted. Season to taste with salt and pepper. Set aside.
Place a chicken breast on each slider bun, cover with spinach mixture and a pice of bacon, followed by the top bun.