Cinnamon Bun Pancakes

Name: Cinnamon Bun Pancakes
Ingredients: 2/3 cup packed light brown sugar; 5 tablespoons unsalted butter, melted; 1 tablespoon ground cinnamon; 1 1/4 cups confectioners' sugar; 4 tablespoons unsalted butter, melted; 3 tablespoons milk; Pinch of fine salt; 1 1/2 cups all-purpose flour (see Cook's Note); 3 tablespoons granulated sugar; 1 tablespoon baking powder; 1/4 teaspoon fine salt; 1/8 teaspoon freshly grated nutmeg; 1 1/4 cups milk, at room temperature; 1/2 teaspoon pure vanilla extract; 2 large eggs, at room temperature; 3 tablespoons unsalted butter, melted, plus more as needed