Heat oven to 350°F (175°C). Grease a 9x13-inch baking dish (or a 4 quart baking dish).
Melt ½ cup (1 stick) butter in a large frying pan over medium heat. Add the 6 cups corn, 1 diced onion and 2-3 diced jalapeños. Season with 2 teaspoons salt and ½ teaspoon pepper. The corn will release some liquid and then start to dry out, when that happens and the onions are tender. It’s ready. About 15 minutes. Set aside to cool slightly.
In a large bowl, whisk together 3/4 cup masa harina, 2 tablespoons sugar, 1 tablespoon baking powder, 1 teaspoon smoked paprika, and 1 teaspoon cumin.
In a separate bowl, whisk together 1 1/2 cups crema, 1 cup cotija, and 2 eggs until smooth. Pour egg mixture and corn mixture into the dry ingredients and stir until evenly combined. It will be thick, that's okay.
Pour the mixture into the prepared dish and bake uncovered for 30-35 minutes, until the top is golden and set. Broil for 2–3 minutes to brown the top.
Top with extra cotija and serve warm.