Preheat over to 400 degrees and line bottom of cast iron skillet with a round of parchment paper. Spray parchment paper and sides of skillet with cooking spray.
Cut the tomatoes into slices and lay on paper towels to drain while you mix the batter.
In large bowl, whisk together cornmeal, flour, baking powder, and salt. Stir in 1 1/2 C cheese, corn, basil, and jalapeno. Make a well in the center.
In another bowl, whisk buttermilk, melted butter, and eggs. Add buttermilk mixture to dry ingredients, stirring until just combined.
Place tomato slices in bottom of prepared skillet, overlapping if needed. Sprinkle with sugar and top with 1/2 C of shredded cheese. Spoon batter onto tomatoes, smoothing.
Bake until golden brown and a wooden pick inserted in the center comes clean - 30-35 minutes.
Let cool in skillet for 10 minutes and then invert bread onto serving platter. Top with remaining 1/4 cup of cheese. Garnish with basil.