Homemade Frosted Brown Sugar Cinnamon Pop Tarts

Name: Homemade Frosted Brown Sugar Cinnamon Pop Tarts
Prep time: 30 min
Cook time: 15 min
Total time: 45 min
Cuisine: American
Ingredients: 3/4 cup light brown sugar; 1 tablespoon all-purpose flour; 1 tablespoon ground cinnamon; 2 tablespoons salted butter, melted; 1 teaspoon vanilla extract; 2 cups all-purpose flour; 1/2 cup whole wheat flour ((or additional all-purpose flour)); 1/2 teaspoon ground cinnamon; 2 sticks (1 cup) cold salted butter, cut into 1/2 inch pieces; 1 egg beaten, for brushing; 2 cups powdered sugar; 1 tablespoon vanilla extract; 1 teaspoon ground cinnamon; cinnamon sugar, for sprinkling (could also use coarse salt - both are optional)