Place the eggs and sugar in the bowl of an electric mixer. Using a whisk attachment, mix on medium speed until thoroughly combined, about 1 minute. Using a paring knife, slice the vanilla bean in half. Add the vanilla seeds, flour, citrus zests, and half of the milk and mix on medium speed until well incorporated. Add remaining milk and cream, continue to mix until the crepe batter is smooth and homogenous. If the batter is lumpy, strain it through a fine-mesh sieve.
Grease an 8-inch nonstick crepe pan (a nonstick frying pan will also work) with about 1 teaspoon of the butter and place over medium-high heat. Once it is hot, wipe away any excess butter with a paper towel. Then pour a small amount of crepe batter, about 2 tablespoons, into the pan and tilt the pan to spread the batter evenly. The batter should barely cover the bottom of the pan. Cook until it browns around the edges, about 30 seconds. Use a large spatula or pancake turner to gently flip the crepe and cook for another 30 seconds. Adjust the level of heat as needed. The crepe should be thin, light, and unevenly browned. Slide the crepe onto a plate and continue to make crepes until all of the batter is used. If the crepes begin to stick to the bottom of the pan, butter the pan again.
Crepes may be stacked directly on top of each other and stored in the refrigerator up to 2 days, well-wrapped. Cold crepes may stick together; warm the crepes slightly in the microwave for 10 to 15 seconds on high power, or in a moderate oven to separate easily.