Step 1Heat the oven to 375 degrees.
Step 2In a medium bowl, whisk together 2 1/2 cups flour and the baking powder.
Step 3In a large bowl, stir together the creamed corn, ricotta cheese, eggs, vegetable oil, one-half cup plus 1 tablespoon cornmeal, one-half cup plus 1 tablespoon sugar, the salt and corn kernels. Stir in the flour mixture a little at a time until incorporated.
Step 4Spoon the mixture into a 10 1/2-inch seasoned cast-iron skillet or similar-sized greased baking pan.
Step 5In a medium bowl, whisk together the remaining two-thirds cup each flour, cornmeal and sugar. Stir in the melted butter until combined to form a crumbly mixture. Drizzle the crumble topping over the corn bread base.
Step 6Bake the corn bread until puffed and lightly browned on top and a cake tester or knife inserted in the center comes out clean, 30 to 45 minutes.