Melt the butter in a medium saucepan over medium heat.
Add the chopped onion and cook until soft and translucent without browning.
Stir in the flour and cook for about 1 minute while stirring constantly.
Gradually whisk in the chicken stock until smooth.
Add the chopped tomatoes with their juice and stir well.
Bring to a gentle boil, then reduce to a simmer.
Stir in the sugar and season with salt and black pepper.
To prepare the dumplings, whisk together the flour, baking powder, salt, pepper, garlic powder, and onion powder.
Cut the cold butter into the flour mixture until it resembles coarse crumbs.
Stir in the grated cheddar cheese.
Add the milk and mix gently until a soft dough forms.
Drop spoonfuls of dough onto the simmering Creamy Tomato Soup with Cheddar Dumplings.
Cover tightly and simmer gently for 10–12 minutes without lifting the lid.
Once the dumplings are fluffy and cooked through, sprinkle with additional cheddar if desired.
Ladle into warm bowls and serve immediately.