1 - Preheat oven to 350 degrees F (175 degrees C).

2 - Pour the milk into a saucepan along with the lemon zest and cinnamon sticks.

3 - Bring to a simmer over medium-high heat, then reduce heat to low, and cook for 5 minutes.

4 - Turn heat off, and allow to steep for 15 minutes.

5 - Gently beat the eggs and sugar together until the sugar has dissolved.

6 - Slowly beat in 1 cup of the hot milk, a little at a time, until it has been incorporated.

7 - Stir the egg mixture back into the hot milk, pour in the pisco, and mix until well combined.

8 - Pour the custard through a fine mesh sieve into a 2-quart ceramic casserole dish to remove the lemon zest and cinnamon.

9 - Bake in preheated oven until set, and browned on top, about 30 minutes.

10 - Chill before serving.