Preheat oven to 350 degrees F.
Spray 9x13" baking dish with cooking spray.
Heat medium pot of water over high heat and bring to boil. Cook pasta according to package, until al dente.
Meanwhile, heat skillet over medium-high heat.
Add salami, and cook until it begins to release its oils.
Add roasted red pepper and spinach, and cook until spinach is wilted.
Remove from heat and place on plate lined with paper towels to get rid of excess liquid/grease.
In large skillet, heat butter over medium heat.
Season with salt.
Add flour, stirring to create a roux. Let cook over medium heat for 2 minutes, stirring constantly.
Slowly add milk, stirring constantly, so milk and flour become incorporated.
Once all of the milk is added, stir in cheese until melted.
Combine cheese sauce with cooked macaroni, salami, red pepper, and spinach.
Stir well to combine.
Pour into prepared dish.
Combine panko bread crumbs and melted butter, stirring until combined.
Sprinkle over macaroni and cheese.
Bake in preheated oven for 30-35 minutes, until cheese is bubbling.
If breadcrumbs are not golden, turn on broiler for 1-2 minutes, watching carefully so they do not burn.
Let sit for 5 minutes, then dig in!
Enjoy!