Preheat oven to 375°F. Grease 1 ½-quart baking dish with 1 tablespoon butter and set aside
Melt 3 tablespoons butter. In a mixing bowl, stir together melted butter with breadcrumbs. Set aside
Bring a large pot of salted water to a boil. Add macaroni and cook until al dente
While pasta cooks, melt 2 Tbsp butter in a saucepan. Whisk in flour; stir 2 min. Gradually whisk in milk, cooking until thick, 2–3 min. Remove from heat, stir in nutmeg, pepper, and cheese until melted
Drain cooked pasta and stir into cheese sauce. Fold in yogurt until evenly combined. Transfer to prepared baking dish and top evenly with breadcrumbs. Bake for 15-20 minutes, or until golden brown
