Preheat oven to 350˚F. Spray a 9" x 9" baking dish with nonstick spray. Set aside.

Bring a pot of water to a boil and cook gnocchi according to instructions, about 3 ½ minutes. Drain and arrange in a single layer at the bottom of the prepared dish.

In a saucepan over medium heat, melt the butter. Stir in garlic and cook until lightly golden, about 1 minute. Whisk in flour until the mixture thickens. Add the milk and whisk until the sauce thickens, for about 3 minutes. Whisk in 1 cup of the cheese. Whisk until smooth. Remove from heat and stir in the sour cream. Season with salt and pepper, to taste.

Pour sauce over gnocchi. Sprinkle the remaining cheese, green onions, and bacon over the gnocchi.

Bake for 25 minutes, or until it is bubbling, and cheese is melted. Remove from oven and let sit for 5 minutes. Serve warm.