01 -  Boil macaroni in salted water according to package directions until al dente. Drain and set aside. 
 02 -  In a large saucepan, melt 2 tablespoons butter over medium heat. Stir in flour and cook for 1 minute, whisking constantly. 
 03 -  Slowly whisk in whole milk until fully incorporated and no lumps remain. Continue to stir until mixture thickens, about 3 to 4 minutes. 
 04 -  Reduce heat to low. Add sharp cheddar, mozzarella, and cream cheese, stirring until completely melted and sauce is smooth. 
 05 -  Mix in Dijon mustard, sriracha sauce, garlic powder, smoked paprika, salt, and black pepper. Taste and adjust level of heat if desired. 
 06 -  Fold in chopped dill pickles and pickle brine, mixing thoroughly. 
 07 -  Stir drained macaroni into cheese sauce to evenly coat. 
 08 -  Set oven broiler (grill) to high heat. 
 09 -  In a small skillet, melt 1 tablespoon butter. Add panko breadcrumbs and cook, stirring, until golden brown. 
 10 -  Transfer mac and cheese to a baking dish, top with toasted panko, and broil for 2 to 3 minutes until the crust is crisp. 
 11 -  Sprinkle with fresh chives before serving, if desired.