Preheat oven to 375 degrees F (190 degrees C). Brush 1 tablespoon butter in bottom and up sides of a 9 1/2-inch deep dish pie plate.

Combine sugar, cinnamon, and salt in a small bowl.

Place 1 sheet of phyllo dough on a cutting board or clean work surface; brush butter over 1 side. Carefully scrunch up phyllo by pushing the short sides towards another to create a rope.

Loosely wrap into a coil and place in the center of the prepared baking dish. Repeat with remaining phyllo sheets and butter, placing and forming around the center coil to form a concentric circle, packing them in tightly.

Sprinkle 2 tablespoons of the spiced sugar mixture on top.

Bake in the preheated oven until golden, about 25 minutes. Remove from oven and reduce oven temperature to 325 degrees F (165 degrees C).

While phyllo bakes, heat milk and cream in a small saucepan over medium heat until it just begins to boil. Remove from heat.

Whisk together eggs, vanilla, and remaining spiced sugar mixture in a bowl; gradually add hot milk, whisking constantly, until combined. Immediately pour spiced milk over phyllo in the baking dish and return to the oven.

Bake until custard is just set, 20 to 25 minutes. Dust with powdered sugar. Serve warm or at room temperature.