Coffee Cake with Orange Marmalade and Orange Glaze

Name: Coffee Cake with Orange Marmalade and Orange Glaze
Ingredients: 3/4 cup all-purpose flour; 2/3 cup packed light brown sugar; 1 teaspoon freshly grated nutmeg; Pinch of fine salt; 5 tablespoons unsalted butter, at room temperature; 1 stick (8 tablespoons) unsalted butter, at room temperature, plus more for the pan; 2 cups all-purpose flour; 1 teaspoon baking powder; 1/2 teaspoon baking soda; 1/2 teaspoon fine salt; 1 cup granulated sugar; 2 large eggs; 2 teaspoons vanilla extract; 1 cup sour cream; 2/3 cup orange marmalade; 3/4 cup confectioners' sugar; 2 tablespoons orange juice; 1 teaspoon finely grated orange zest plus orange slices, for serving