Preheat oven to 425. While oven is preheating, blend eggs, milk, cream, flour, salt, nutmeg, lemon flavor, and sugar well with mixer or blender. Set batter aside. Bring 1/3 cup water to boil in small pan. Add blueberries, cover, and reduce heat. Allow to simmer during next step.
Divide stick of butter evenly into 3 rounded, 2 Qt/1.9 L baking dishes. Place all three baking dishes on middle rack of preheated oven. Heat for two minutes to melt butter.
Carefully retrieve hot baking dishes from oven. Gently swirl each to coat with melted butter prior to setting on hotpad. Don't burn yourself! Pour 1/3 batter into each hot dish and return to oven. Bake for 20 minutes until puffy and lightly browned.
While Dutch Babies are baking, drain cooked blueberries, reserving liquid, and return berries to pan. Sweeten with agave or honey. Keep warm. Stir hot blueberry juice into lemon curd until mixture takes on dark blue color and becomes fluid enough to drizzle on hot cakes (about 3 tablespoons). Keep warm.
Remove Dutch Babies from oven and divide each in half. Drizzle each plated half with warm lemon curd sauce. Top each with 1/2 cup warm blueberries and a dusting of powdered sugar.