1. If using store bought or leftover mac and cheese, skip to step 3. 
2. For homemade mac and cheese: melt butter in a medium saucepan over medium heat. Stir in flour and stir constantly for 30-60 seconds.  As soon as flour starts to turn a little brown, add milk to roux slowly, whisking constantly to fully incorporate.  Cook, stirring occasionally to avoid milk scorching on the bottom of the pan, until thickened.  Stir in 3 cups of shredded cheese and season generously with Kosher salt. 
3. Combine cooked macaroni with cheese sauce in a large bowl.  Stir in remaining 1 cup of shredded cheese.
4. Spread in an even layer in a baking dish sprayed with nonstick cooking spray.  Let cool and refrigerate until firm, at least 2-4 hours but preferably overnight.
5. Using a small cookie scoop, scoop mac and cheese into balls and place on a parchment lined baking sheet.  Freeze for 2 hours.
6. Meanwhile, finely crush Doritos and place in a medium bowl.  Whisk together milk and eggs in a small bowl.
7. Heat enough canola or vegetable oil in a medium skillet or saucepan to cover half of the mac and cheese balls over medium/medium-high heat.  Remove mac and cheese balls from freezer.  Dip in egg wash and thoroughly cover with crushed Doritos.  Fry mac and cheese balls in batches, flipping once, until golden brown and crispy, about 2-4 minutes.
8. Serve Doritos Mac and Cheese Balls with Sriracha Mayo.  Devour.

for the Sriracha Mayo

1. Combine the mayo, Sriracha, and sugar in a small bowl and season with Kosher salt.  Set aside and let flavors meld for at least 20 minutes.  Can be made ahead and stored in the refrigerator for up to one week.