Prep the kale: Rinse well, strip the tough stems, and chop the leaves into bite-size pieces. Pat dry to avoid watering down the sauce.
Warm the aromatics: Heat olive oil in a large skillet over medium.
Add shallot and a pinch of salt; cook 2–3 minutes until translucent. Stir in garlic and red pepper flakes; cook 30–60 seconds until fragrant.
Bloom the tomatoes: Add sun-dried tomatoes and cook 1 minute to coat in the oil and wake up their flavor.
Wilt the kale: Add kale in batches with a pinch of salt. Toss as it wilts, 3–5 minutes, until deeply green and reduced by about half.
Deglaze: Pour in broth and scrape up any browned bits.
Simmer 2 minutes to soften the kale further.
Make it creamy: Lower heat. Stir in heavy cream and bring to a gentle simmer. Cook 3–4 minutes, stirring, until slightly thickened and glossy.
Add cheese: Sprinkle in Parmesan and stir until melted and smooth.
If using Italian seasoning or butter, add now.
Finish bright: Stir in lemon zest and 1 teaspoon lemon juice. Taste and add more lemon, salt, or pepper as needed. The sauce should taste balanced and lively.
Serve: Spoon into bowls or over pasta, rice, or toasted bread.
Finish with extra Parmesan and a crack of pepper.