1. In a large skillet, heat olive oil and butter on high flame. Add the chopped garlic, and cook for a minute, stirring till its golden brown.
2. Add the bite size chicken pieces, and cook till golden brown on the outside. Reduce heat to medium, add salt, pepper and red chilli flakes and cook the chicken till cooked through.
3. Remove from heat. In a large pot of boiling salted water, cook the pasta according to package directions.
4. Add the broccoli florets during the last 2-3 minutes of cook time. Drain, reserving a bit of the pasta water and set aside.
5. In a large skillet, melt the butter. Add the garlic and cook for a minute.
6. Add the flour and cook it for about a minute, stirring continuously. Slowly whisk in milk and chicken stock, making sure no lumps are formed.
7. Add salt, pepper, mustard powder, grated nutmeg, and  red chilli flakes. Cook, stirring constantly, until mixture thickens.
8. Remove from heat and add the cheese, stirring until melted.
9. Add the pasta, broccoli and chicken and stir to combine. If sauce is too thick, add the reserved pasta water a tbsp. At a time, till desired consistency.

Enjoy your meal!