Cauliflower Casserole with Everything Bagel Seasoning

Name: Cauliflower Casserole with Everything Bagel Seasoning
Ingredients: 1 teaspoon unsalted butter, plus 4 tablespoons, divided; 4 cloves garlic, thinly sliced; 1 teaspoon kosher salt, divided; ½ teaspoon ground pepper, divided; ⅓ cup all-purpose flour; 3 cups whole milk; 2 large heads cauliflower, cored and cut into 2-inch florets; ¼ cup finely sliced chives, divided; 1 ⅓ cups finely grated Parmigiano-Reggiano cheese (3 ounces); ½ teaspoon cayenne pepper (Optional); 3 tablespoons toasted sesame seeds; 1 tablespoon poppy seeds; 1 ½ teaspoons caraway seeds