Step 1: Prepare the Caramel - In a medium saucepan, combine 1 cup of granulated sugar and 1/4 cup of water. Cook over medium heat, swirling the pan gently until the sugar dissolves. Continue to cook without stirring until the mixture turns a deep amber color. Pour the caramel into the bottom of your ramekins, swirling to coat.
Step 2: Make the Custard Mixture - Heat 5 cups of milk over medium heat until warm. In a separate bowl, whisk together 1 cup of sugar, 1/2 teaspoon salt, and 6 eggs until blended. Gradually add the warm milk to the egg mixture, whisking continuously.
Step 3: Add Flavor - Stir in 1 tablespoon of vanilla extract and the strips of orange peel to the custard mixture. Mix well.
Step 4: Strain the Mixture - Pour the custard mixture through a fine strainer into a large bowl to remove the orange peel and lumps.
Step 5: Fill the Ramekins - Carefully pour the strained custard mixture into the prepared ramekins over the caramel layer.
Step 6: Create a Water Bath - Place the filled ramekins in a baking dish and fill the dish with hot water until it reaches halfway up the sides of the ramekins.
Step 7: Bake - Preheat your oven to 325°F (160°C). Bake for about 45-50 minutes, until the custard is set but slightly jiggly in the center.
Step 8: Cool and Serve - Once baked, cool to room temperature. Refrigerate for at least 4 hours. To serve, run a knife around the edges of each ramekin and invert onto a plate.