In a medium bowl, sift together the flour, sugar, baking powder, and salt. Add the onion and scallions to the bowl and stir well. Drizzle the quarter cup of melted butter over the mixture and stir well to fully incorporate.
Make a hollow in the center of the mixture, pour in the milk, and stir well to fully incorporate, making sure that there are no lumps. It might seem too runny at first, but the masa Will absorb the butter and milk, so after 20 to 30 minutes it will be a nice, thick batter.
Preheat the oven to 350°F
Heat a 10 or 12 inch cast iron skillet over medium high heat, and add the remaining butter. Just as it starting to bubble but not Brown, poor in the batter to cover the bottom of the skillet. It should be half to 1 inch thick. Once the batter begins to bubble up a bit on the sides, move the skillet to the oven.
After 15 minutes, remove the pan from the oven to check the cake for doneness by inserting a fork into the center and taking a peek inside. Rotate the pan when you put it back into the oven and check the cake every five minutes for doneness. Once there’s nothing gooey in the center and the fork comes out dry, the cake is done. It should cook for 25 to 30 minutes total.
Let the cake rest in the skillet at room temperature for five minutes before serving it.
On the stove top, Grill, or in the oven, char the jalapeños until they collapse. Place them in a bowl and tightly cover with plastic wrap for several minutes, allowing them to sweat and steam. With wet hands, skin and deseed the peppers, and then mince the flesh.
Put the butter in a medium bowl and fold in the jalapeños, honey, and salt until fully incorporated. Set aside until ready to use, or store in an airtight container in the refrigerator for up to two weeks.