In a large pot over medium heat, melt 2 tablespoons of butter until bubbly. Add one diced onion and sauté for about 5 minutes until it becomes translucent and fragrant.

Sprinkle in 2 tablespoons of flour and stir constantly for 1 minute, until the mixture is smooth and golden.

Gradually pour in 4 cups of chicken broth, stirring smoothly to combine. Add 28 ounces of canned tomatoes and bring the mixture to a boil.

Once boiling, reduce the heat to a gentle simmer and add 1 teaspoon of sugar, along with salt and black pepper to taste. Let it simmer uncovered for about 15 minutes.

Carefully ladle half of the soup into a blender, blending until creamy, then return it to the pot.

In a separate bowl, prepare 1 ½ cups of biscuit mix according to package instructions, adding 1 cup of shredded cheddar cheese.

Using a spoon, drop dollops of the biscuit mixture into the simmering soup, cover the pot and cook for 15-20 minutes on low heat.

Once the dumplings are fluffy and cooked through, melt 1 tablespoon of butter and mix it with a seasoning packet. Brush this mixture over the tops of the dumplings.

Remove the pot from heat and ladle the soup into bowls with the dumplings. Serve hot.