In same pot, melt butter over medium heat. Add flour and whisk until combined. Slowly add half and half, bring to a boil, and stir until thickened, about 2 minutes.
Turn heat to low, add cheeses, and stir until cheeses are completely melted.
Add pasta and stir until noodles are well coated.
Separate mac and cheese into four plates, top with cooked chicken (optional), and drizzle with Sriracha.
Recipe by Simple, Sweet & Savory at https://www.simplesweetsavory.com/creamy-mac-and-cheese-with-sriracha/