Preheat oven to 375 degrees. Grease a mini muffin pan well with butter or shortening.

In a small bowl, mix together the melted butter and panko breadcrumbs. Add the kosher salt, freshly ground black pepper, Italian seasoning, garlic powder, and Parmesan cheese.

Put a large pot of salted water on the stovetop to boil. Add the elbow macaroni and cook al dente according to the package instructions. Drain the noodles well.

Meanwhile, melt the butter in a large skillet over medium heat. Whisk in the flour and continue cooking while whisking constantly for 2 minutes. Slowly add the milk and continue cooking while whisking frequently until it thickens.

Reduce the heat to as low as it will go, and add 1 1/2 cups of shredded cheddar. Remove from the heat and season with salt and pepper to taste.

In a large bowl, mix together the cooked and drained elbow macaroni, cheese sauce, beaten egg, remaining shredded cheddar cheese, and sour cream. Divide the macaroni and cheese mixture evenly into a well-greased mini muffin pan. Top each cup with 1 heaping teaspoon of the breadcrumb mixture.

Bake in a preheated oven for 15-17 minutes. If desired, pop them under the broiler on low for 1-2 minutes to lightly brown the tops.

Allow them to cool for 10 minutes. Then run a knife around the edge and gently remove them.