In a medium saucepan, melt the butter over medium-high heat. Add the garlic and cook for 1 minute until fragrant. Whisk in the zest and flour, then whisk in the milk. Whisk and stir for 4 minutes. Add the cheeses and continue to whisk and cook until melted and slightly thickened. Remove from heat and set aside.
COOK THE SHRIMP:
In a medium nonstick skillet, melt the butter over medium-high heat. Add the garlic and cook for 1 minute until fragrant. Add the shrimp and a sprinkle of salt and pepper. Saute until shrimp is pink and cooked through. Remove the shrimp from the pan and set aside.
FINISH THE DISH:
Add the spiral zucchini noodles (zoodles) to the skillet and cook over medium heat for just a couple of minutes- until the zucchini is slightly wilted. You don't want to cook them too much or they'll get watery and mushy. Add the alfredo sauce to the skillet and toss to combine with the zoodles.
Divide the zoodles between three bowls. Top with shrimp and sprinkle with bacon and parsley (if using). Add salt and pepper, as desired. Serve immediately.