Preheat oven to 375 degrees F (190 degrees C).
Grease muffin cups or line with paper muffin liners.
In a large bowl, combine flour, baking powder, baking soda, salt, basil, oregano and sugar into large bowl; stir until well blended.
Mix in tomatoes, 1 1 /2 cups of cheese and onions.
In another bowl beat egg, whisk in buttermilk and stir until combined.
Spoon batter into muffin tins until half full.
Sprinkle remaining 1 cup cheese on top of muffins.
Bake in preheated oven for 15 to 20 minutes, until a toothpick inserted into center of the muffin comes out clean.