In a medium-large stock pot or Dutch oven, heat the olive oil over medium heat.

Add the rosemary sprig and fry it gently in the hot oil for about 1 minute. You will remove the rosemary after the soup simmers, so let it infuse its flavor with the other ingredients.

Next, add the diced onion and cook until it becomes translucent, which should take around 5 to 6 minutes.

Stir in the minced garlic, tomato paste, and crushed red pepper flakes, mixing well.

Cook this mixture until the tomato paste turns a brick-red color and the garlic becomes aromatic, approximately 2 to 3 minutes.

Add the dried oregano and sun-dried tomatoes, cooking for an additional minute.

Incorporate the butter beans, vegetable broth, salt, and black pepper, then increase the heat to bring the soup to a simmer.

Allow the soup to gently simmer uncovered until it reduces slightly, about 15 minutes.

Remove the rosemary sprig from the pot.

Using an immersion blender, blend about half of the soup until smooth, or carefully transfer 2 cups of the soup to an upright blender and blend until mostly smooth.

Return the blended soup to the pot and add the chopped kale and heavy cream.

Continue cooking until the kale is wilted and bright green, which should take about 2 to 4 more minutes.

Stir in the red wine vinegar and adjust the seasoning with additional salt and black pepper if necessary.

Ladle the soup into bowls and garnish with freshly grated Parmesan cheese.