In a large pot or deep skillet, melt butter over medium heat.
Add minced garlic and sauté until fragrant, about 1 minute.
Pour in chicken broth and milk, stirring to combine.
Add uncooked pasta, salt, pepper, and red pepper flakes if using.
Bring to a boil, then reduce heat to low and cover. Simmer for 12-15 minutes, stirring occasionally, until pasta is al dente.
Stir in heavy cream and Parmesan cheese until melted and creamy.
Garnish with fresh parsley and serve immediately.