Heat olive oil in a large pot or Dutch oven over medium heat. Add diced onion and cook for 5 to 7 minutes until soft and translucent. Add minced garlic and cook for 1 more minute until fragrant.

Stir in crushed tomatoes, tomato sauce, broth, oregano, and optional sugar. Bring to a simmer, then reduce heat to low. Cover and cook for 15 minutes.

Blend soup to desired smoothness using an immersion blender or regular blender in batches. Stir in heavy cream. Season with salt and pepper. Return to a gentle simmer. Do not let it boil once cream is added.

Whisk together flour, baking powder, garlic powder, and salt. Cut in cold butter until mixture resembles coarse crumbs. Stir in cheddar and milk until just combined. Do not overmix.

Drop heaped spoonfuls of batter onto the simmering soup, spaced apart. Cover immediately with a tight-fitting lid.

Steam dumplings for 12 to 15 minutes without lifting the lid. They are done when a toothpick comes out clean and the tops look set and matte.

Mix melted butter, dried parsley, garlic powder, and a pinch of salt. Brush over cooked dumplings. Serve immediately, garnished with fresh basil if desired.