In a large pot, melt 2 tablespoons of butter over medium heat. Once melted, add in one chopped onion and sauté for about 5 minutes, stirring occasionally until the onion becomes translucent and fragrant.

Stir in 2 tablespoons of flour, cooking for 1 minute while continuously stirring to form a roux.

Gradually pour in 4 cups of chicken broth and one 28-ounce can of diced tomatoes, stirring expertly to combine.

Once boiling, reduce the heat and let it simmer for about 10 minutes. Stir in 1 teaspoon of sugar, along with salt and black pepper to taste.

For a creamier texture, carefully blend half of the soup using an immersion blender, then return the soup to the pot.

In a mixing bowl, prepare the biscuit mix according to package instructions, adding 1 cup of shredded sharp cheddar cheese.

Drop spoonfuls of the biscuit mixture directly into the simmering soup. Cover the pot with a lid and let the dumplings steam for 15-20 minutes.

Melt 2 tablespoons of butter and mix it with any remaining seasoning from the biscuit mix. Brush this mixture over the dumplings right before serving.