Preheat the oven to 375°F (190°C). Spray a 6-cup jumbo muffin pan generously with nonstick cooking spray. In a small bowl, stir together the melted butter and zest from 2 oranges until well combined. Set the orange butter aside.

Prepare the phyllo layers: Unwrap the thawed phyllo dough and keep it covered with a slightly damp kitchen towel to prevent drying. Brush a phyllo sheet with orange butter and place another sheet on top; repeat with another two phyllo sheets. Fold the 2 sets of stacked phyllo sheets accordion-style, the long way, with your hands. Take one accordion-style strip and roll it like a pinwheel. Continue wrapping the second strip around the first spiral, creating a larger pinwheel. Place the phyllo pinwheel into one of the muffin pan wells; the phyllo should fill the well with loose, flowing layers and a rose-like spiral shape. Brush with enough orange butter to generously coat all the folds. Repeat with the remaining phyllo sheets and orange butter to create 5 more phyllo pinwheels.

Bake for 15–20 minutes, until the phyllo is crisp to the touch; the edges should be just turning golden, but the centers can be pale. Remove from the oven, and keep the oven on.

Make the filling: While the phyllo bakes, whisk together the milk, sugar, vanilla, eggs, and zest from 1 orange in a medium bowl until smooth.

Make the orange blossom syrup: Combine the orange juice, sugar, and orange peel strips in a small saucepan over medium heat. Bring to a boil, stirring occasionally, until the sugar dissolves completely, about 3–4 minutes. Remove from the heat and let cool completely. Once cooled, remove and discard the orange peel strips. If using, stir in the orange blossom water, starting with 1 teaspoon. Taste, and add up to 2 teaspoons total, depending on how strong you want the floral flavor. Set aside.

Once the phyllo cups have finished baking, carefully pour the custard mixture evenly into each one, filling them about ¾ full; this keeps the phyllo edges exposed so they stay crispy. Evenly sprinkle the chocolate chips over the custard in each cup.

Return the muffin pan to the oven and bake for 20–25 minutes, until the custard is completely set and no longer jiggles when you gently shake the pan. The phyllo should be deeply golden brown and crisp.

As soon as the crinkle cakes come out of the oven, use a spoon to drizzle 2 tablespoons of the cooled orange blossom syrup evenly over each cake. Let the syrup-coated cakes cool completely in the pan, about 30–40 minutes. Use a spoon or offset spatula to carefully remove each cake from the pan and place it on a serving platter. With a fine-mesh sieve, generously dust the tops with powdered sugar, and sprinkle with fresh orange zest for a pop of color. Serve at room temperature.