Preheat oven to 375°F (190°C).
Scoop out the centers of halved zucchinis and set them aside.
In a saucepan over medium heat, melt the butter. Whisk in the flour and cook for 1-2 minutes until lightly browned.
Gradually whisk in milk, continuing to whisk until the mixture thickens, about 3-5 minutes.
Remove from heat and stir in the shredded cheddar cheese until melted and smooth.
Add the cooked elbow macaroni to the cheese sauce, then season with salt and black pepper, mixing well.
Spoon the mac and cheese mixture into the hollowed-out zucchini halves.
If desired, sprinkle bread crumbs on top for added crunch.
Place stuffed zucchinis on a baking sheet and bake in preheated oven for 25-30 minutes, or until zucchinis are tender and tops are golden brown.
Serve warm and enjoy!