Start by dicing the shallot and mincing the garlic cloves, then set aside. Chop the bacon into ½-inch pieces. In a large pot, bring 2.25 cups of chicken stock to a boil and add the chicken breasts, simmering for 10-12 minutes until cooked through. While the chicken cooks, fry the bacon in a separate skillet over medium-high heat until crispy, about 5-7 minutes, then transfer to a paper towel-lined plate. Once the chicken is cooked, remove it from the stock, let it cool slightly, then slice or shred it into bite-sized pieces.
In the skillet with bacon fat, sauté the diced shallot over medium heat for 2-3 minutes until softened, then add the minced garlic and cook for another 30 seconds until fragrant. Pour in the remaining 1.75 cups of chicken stock, milk, and lemon juice, bringing to a gentle simmer. Add the creamy cheese in chunks and whisk continuously until completely melted and smooth.
Stir in the dried parsley, dried chives, onion powder, dill, garlic powder, and smoked paprika, mixing well to distribute the seasonings evenly. In a small bowl, mix the cornstarch with 1 tablespoon of cold water until you have a smooth slurry, then whisk this into the simmering sauce. Cook for 1-2 minutes, stirring constantly, until the sauce thickens slightly and coats the back of a spoon. Season with salt and black pepper to taste.
Add the sliced cooked chicken from Step 1 to the sauce, then bring the mixture to a gentle boil and add the gnocchi. Cook for 5 minutes, stirring occasionally, until the gnocchi is heated through and floats to the surface.
Transfer the chicken and gnocchi mixture to a 9x13-inch baking dish. Distribute the shredded cheddar cheese evenly over the top, then lightly spray the surface with olive oil spray to help the cheese brown evenly. Place under the broiler for 2-3 minutes, watching carefully, until the cheese is melted and lightly golden.
Remove the dish from the broiler and let it rest for 1-2 minutes so the cheese sets. Top with the crispy bacon from Step 1 and fresh parsley, then serve immediately while the gnocchi is hot and creamy.