Heat 1 tablespoon of olive oil over medium heat in a large Dutch oven. Add the chopped shallot and cook for 2 minutes, stirring often, until softened.
Add 1 cup of orzo to the pot and stir constantly for 2 minutes, toasting it until lightly golden and fragrant.
Pour in 2 cups of chicken broth, kosher salt and pepper, and lemon zest. Bring to a simmer, then reduce the heat to medium-low. Cook, stirring occasionally, for 8–10 minutes or until the orzo is tender and the liquid is mostly absorbed.
Stir in the juice of the lemon, ½ cup of heavy cream, ¼ cup of Parmesan cheese, and 2 tablespoons of butter. Add the crushed red pepper flakes if using. Stir until everything is melted, silky, and well combined. Season with additional with kosher salt and black pepper to taste if needed.
Spoon the creamy orzo into bowls. Top with extra Parmesan, a sprinkle of finely grated lemon zest, and a drizzle of olive oil if you’d like.