Martha made this recipe on Martha Bakes episode 407.
Preheat oven to 350 degrees. Brush a 14-inch round cake pan with some of the clarified butter; set aside.
Place 1 sheet of phyllo dough on work surface with one long side parallel to edge of work surface. Using your hands, loosely ruffle phyllo by pushing short sides toward one another to create a long cylindrical shape. Place upright in center of prepared cake pan, creating a spiral. Repeat process with remaining sheets, continuing spiral outward until bottom of pan is covered.
Using a pastry brush, brush remaining clarified butter all over phyllo in pan; sprinkle with 1/4 teaspoon cinnamon. Transfer to oven and bake until golden brown, 25 to 30 minutes.
Meanwhile, heat milk in a medium saucepan until it just barely begins to boil; remove from heat. Whisk together eggs and sugar in a large bowl. Gradually add heated milk, a little bit at a time, whisking constantly; whisk in vanilla.
Spoon milk mixture over baked phyllo, evenly covering surface. Return pan to oven and bake until filling has set, 25 to 30 minutes more. Dust with confectioners' sugar and cinnamon; serve immediately.