To start the custard, preheat your oven to 325° Fahrenheit (165° C).
Heat the cream over medium-low heat. Meanwhile, slice the vanilla bean in half lengthwise. Scrape out the seeds, using the back of the knife. Add the seeds and the vanilla bean to the cream, along with the finely-grated orange zest. Whisk everything together and let the cream come to a simmer.
Meanwhile, place a bowl onto a wet towel to hold it in place. Whisk the eggs and sugar together. Once the cream comes to a very gentle boil, add a small amount to the eggs to temper them. Continue to whisk as you slowly add the rest of the cream.
Strain the custard mixture into a pitcher or large measuring cup. Next, place the ramekins into a large casserole dish with at least 2” -inch sides. Pour the custard into the ramekins, filling them only about three-quarters full.
We used 3 1/2" -inch x 1 1/2" -inch ramekins, but you can use any size you like. Just keep in mind that different sizes will affect the cooking time.