Preheat oven to 350°. In a large pot of salted boiling water, cook macaroni until just tender, 5 minutes. Drain and transfer to a large bowl.
To bowl, add butter and egg and stir until butter is melted and egg is thoroughly coating noodles. Add onion, garlic, and mustard powders, then pour in milk and cream cheese and stir until combined. Add 1½ cups each cheddar and fontina and stir until macaroni are completely coated.
Butter a 12-cup muffin tin and spoon mixture into cups. Top with remaining cheddar and fontina.
In a small bowl, stir together panko and olive oil and season with salt. Top mac and cheese with panko mixture and season with pepper.
Bake until the cups feel firm and cheese is golden, 30 minutes. Let cool in muffin tin for 10 minutes, then run a knife along the edge of each to loosen.
Garnish with parsley and serve.
Recipe by The Best Video Recipes for All at https://recipes-for-all.com/muffin-tin-mac-cheese/