Clean and chop the leek into slices around 1/3 inch wide.
Place a large frying pan over medium heat and add the butter and crushed garlic. Cook for 2 minutes, stirring occassionally.
Add the leeks and stir often for 5 minutes until they start reducing.
Add the chopped red chili pepper.
Stir the leek mixture to avoid sticking and reduce the heat to low.
Add flour and stir well to ensure no lumps form.
Add the parmesan and milk and stir continuously until the liquid thickens.
Season to taste with salt and pepper and serve immediately.
Video
Notes
When choosing the pepper to use, consider both the heat and overall flavor. They will both impact the eating experience in this recipe. Some good options:
Red jalapeño: Lower medium heat, slightly sweet and bright
Fresno pepper: Lower medium heat, sweet, fruity, and slightly smoky
Malagueta pepper: Upper medium heat, sweet, and tangy