In a saucepan, melt the butter over medium heat. Add the diced onion and sauté until translucent, about 5 minutes.

Stir in the minced garlic and cook for an additional minute until fragrant.

Sprinkle the flour over the onion and garlic mixture, stirring constantly for about 1 minute to create a roux.

Add the diced tomatoes (with juice) and chicken broth, stirring to combine. Bring to a simmer.

Add sugar, salt, black pepper, and red pepper flakes. Simmer for 10-15 minutes until thickened, stirring occasionally.

Remove from heat and garnish with fresh basil. Serve over biscuits or rice.