In a medium bowl, place all the flour, yellow cornmeal, baking powder, and salt.
In a blender, place the sweetened condensed milk, sour cream and 1 cup corn kernels, and blend on high speed until smooth.
In a large bowl, place the butter and sugar and mix until the butter is fluffy and creamed. Add the eggs, one at a time, and mix until smooth. Add half of the wet mixture and half of the dry ingredients and mix on medium speed, scraping the sides of the bowl. Add the remaining wet mixture and remaining dry ingredients and mix until smooth. Fold the remaining corn into the batter.
In a greased 9x9-inch square baking pan, place the batter. Cover loosely with foil. Place in the oven and bake for 20 minutes. Remove the foil and continue baking for about 35 to 45 minutes, or until the sides are light brown or until toothpick inserted in the center comes out almost clean.