For the Lemon Curd:

1. Put the lemon juice and zest in a pot over medium heat. Add the sugar and stir until it dissolves. Reduce the heat to low, making sure the mixture is below a simmer, and whisk in the butter and eggs. Stir almost constantly, keeping the mixture below a simmer, until it thickens, about 8 minutes. Strain through a fine-mesh strainer into a bowl. Cover with plastic wrap, pushing the plastic wrap directly onto the surface of the lemon curd, and then cool completely.

For the Blueberry Syrup:

1. Place the blueberries, water, sugar, and lemon zest in a small pot and bring to a simmer, stirring frequently. Whisk in the cornstarch. Simmer until the berries are soft and the juices have thickened slightly, about 10 minutes. Whisk in the maple syrup and keep warm until ready to serve.

For the Waffles:

1. Separate the eggs and reserve the whites. To the yolks, add the buttermilk, oil, sugar, lemon curd, lemon zest, and vanilla and mix well to combine everything. Stir together the poppy seeds, flour, baking powder, and salt in another bowl and then mix into the wet ingredients.
2. Using a whisk or hand blender, beat the egg whites until fluffy (soft peaks should form when you lift out the beaters/whisk). Gently fold the egg whites into the batter.
3. Preheat the waffle iron and spray with nonstick cooking spray. Pour mixture onto the waffle iron when hot (amount will depend on your iron). Cook according to manufacturer directions (usually a couple minutes per side). Serve warm topped with additional lemon curd, fresh blueberries, whipped cream, powdered sugar, and the blueberry syrup.