Whisk together buttermilk, pickle juice (optional), 1/2 Tbsp Cajun seasoning, and 1 Tbsp Bouillon in large bowl until well blended. Fully submerge chicken in mixture. Set aside.
In separate shallow bowl, whisk together flour, baking powder, cornstarch, and remaining 1/2 Tbsp. each Bouillon and Cajun seasoning until blended. Drizzle 2 Tbsp. buttermilk mixture into flour mixture and gently mix with a fork to create a few clumps that will help form a thick crust.
Pour vegetable oil into large skillet until about ½-inch deep. Heat over medium-high heat until 350°. Dredge chicken pieces into flour mixture gently pressing, including any clumps, to help form a thick crust. Continue until all chicken pieces are well coated. Set aside
Meanwhile, prepare Knorr Sides using the milk and water, following package directions.
Add chicken to hot oil (in batches if necessary) and fry 5 minutes, turning occasionally until chicken is browned and thoroughly cooked.
To build your Mac 'n Chicken Bowl, evenly spoon Knorr sides into 4 serving bowls, then evenly top with crispy chicken and shredded cheddar cheese.