Step 1: In a large pot, bring generously salted water to a rolling boil. Add your chosen pasta and cook according to package directions until al dente. Before draining, reserve about 1/2 cup of the starchy pasta water.
Step 2: While the pasta cooks, heat 2 tablespoons of unsalted butter in a large skillet over medium-high heat. Add the chicken bites, seasoning them generously with salt, pepper, and Italian seasoning. Sauté for 5-7 minutes, stirring occasionally, until the chicken is golden brown and fully cooked. Remove the chicken from the skillet and set aside.
Step 3: In the same skillet, add the remaining 2 tablespoons of butter and half of the minced garlic. Sauté for 1-2 minutes until the garlic is fragrant and lightly golden, being careful not to burn it.
Step 4: Reduce the heat to low. Pour in the heavy cream, stirring constantly to combine it with the garlic butter. Gradually add the grated Parmesan cheese and garlic powder, stirring until the cheese is melted and the sauce is smooth and creamy. If the sauce is too thick, slowly add small amounts of the reserved pasta water until it reaches your desired silky consistency.
Step 5: Return the cooked chicken bites to the skillet. If using, add the fresh spinach and stir everything together until the chicken is rewarmed and the spinach has wilted into the creamy sauce.
Step 6: Add the drained, cooked pasta directly into the skillet with the chicken and sauce. Toss everything gently to ensure every strand of pasta is coated in the luscious sauce. Taste and adjust seasoning with salt and pepper as needed.
Step 7: Divide the pasta into bowls, topping each serving with a sprinkle of fresh chopped parsley. Serve immediately and enjoy your homemade garlic butter chicken bites with savory creamy Parmesan pasta!