Preheat oven to 375°F and spray a 24-cup mini muffin tin with cooking spray to ensure easy release and a crisp crust.

Boil elbow macaroni in salted water until just al dente (about 6 minutes), then drain and rinse under cool water.

In a saucepan, melt butter over medium heat, whisk in flour until bubbly, then gradually whisk in milk until thick.

Remove sauce from heat, stir in shredded cheddar and mozzarella until smooth and creamy; season with salt, pepper, and optional mustard powder.

Mix the pasta and cheese sauce gently in a bowl, ensuring every noodle is evenly coated with gooey goodness.

Spoon the mixture onto a lined baking sheet, chill in the fridge for 15 minutes to firm up for easier shaping.

Using a mini ice cream scoop or spoon, form 24 uniform bites and place them back into the prepared muffin tin.

Dip each bite in beaten egg, then roll in panko breadcrumbs until fully coated, tapping off any excess crumbs.

Bake in the preheated oven for 15–20 minutes, or until golden brown and crisp on the outside.