Preheat oven to 350°F. Grease a 9x13" baking dish. Set aside.
Bring a large pot of salted water to boil. Add pasta and cook according to package directions. Drain, drizzle with olive oil and mix to combine to prevent sticking.
Melt 4 tablespoons butter in a medium saucepan over medium heat. Add flour, salt and garlic powder, and whisk for 1 minute. Add milk and whisk until smooth. Bring to a simmer, or until thickened, and remove from heat.
Add both cheeses and whisk together until completely melted. Combine cheese sauce, cooked pasta, and 3/4 of the chopped bacon in a large mixing bowl. Pour mixture into the prepared baking dish and sprinkle with remaining bacon.
Mix together panko bread crumbs and 1 tablespoon melted butter in a small bowl. Sprinkle over mac and cheese. Bake 30-35 minutes until bubbly and lightly golden-brown.