Chicken and Spinach Pasta Bake

dry pasta (I used a combination of rotini, farfalle and penne. Any similar size would work.)

butter

onion, chopped

garlic, minced

chive and onion cream cheese

sour cream (or plain Greek yogurt)

whole milk, heavy cream or half-and-half (I used half-and-half)

shredded or grated Parmesan cheese

shredded mozzarella cheese

salt

black pepper

crushed red pepper flakes (optional)

chopped fresh spinach

cooked chicken (cubed or shredded)

fresh tomatoes, cut into large chunks (I used grape tomatoes sliced in half)

Fresh basil or parsley, for garnish