Preheat oven to 350°F and liberally grease two 24-count mini muffin pans.
Place the butter in a small saucepan and melt it over medium-low heat until foamy. Add the panko breadcrumbs and fry the mixture until golden. Set aside.
Pour the macaroni into a medium pot with just enough water to cover it. Add ½ teaspoon salt and bring to a boil. Reduce heat to medium and cook for 6-8 minutes, stirring frequently, until the macaroni has absorbed most of the water and is almost al dente (not fully cooked).
Pour in the evaporated milk, and add the garlic and onion powder, ½ teaspoon salt, and a pinch of cayenne. Stir to combine and bring to a boil. Reduce heat to medium-low and add the cheese; stir until the cheese has melted and is smooth. Reduce the temperature to low and let the sauce simmer for 5 minutes until the pasta is creamy.
Remove the pot from the heat and let the mixture sit for five minutes. It will thicken as it cools.
Place a heaping scoop into each of the muffin pan cups. Press the mixture down lightly with a spoon to compact it.
Sprinkle the tops with the breadcrumb mixture.
Place in the oven and bake until the cheese is bubbling and the breadcrumbs are golden brown, about 10-12 minutes. Place the muffin pan on a wire rack to cool for 5 minutes.
Run a sharp knife along the edges of the Mac and Cheese Bites to loosen them from the pan.
Transfer them to a platter and keep them warm until ready to serve, garnishing with parsley or chives, if desired.