Line a baking sheet with parchment paper and preheat the oven to 350 degrees.
Use a large bread knife to cut the buns open, separating the top from the bottom.
Place the buns on the sheet pan, tops of the slider buns facing down and bottom buns facing up.
Spread half of the secret sauce on the bottom buns.
Layer with cheese and beef.
Use a pastry brush to brush the top of the buns with melted butter and sprinkle with sesame seeds.
Bake in the oven for 10-15 minutes or until the cheese melts and the tops of the buns start to brown.
Remove from the oven and layer with remaining classic big mac toppings: crisp lettuce, onion and dill pickles.
Top with the remaining special sauce.
Finish off with the top buns and cut into mini big mac sliders.