Cast Iron Skillet Cornbread

My grandmother's cornbread recipe doesn't have measurements, just instructions like "enough buttermilk to make it pour slow" and "get the skillet smoking before you add the batter." I've been trying to reverse-engineer the ratios for 3 semesters now. What actually matters is the technique: preheating the cast iron with a tablespoon of bacon fat until the fat shimmers. Then pouring the batter in so it sizzles and forms a crust on contact with the hot surface. Crust is the whole thing. Golden and crisp on the bottom while the inside stays dense and slightly crumbly, not cakey the way boxed mixes turn out when you follow the directions on the back. My 10-inch skillet weighs probably 8 pounds and has been seasoned so many times the surface is almost reflective. All that thermal mass is why the bottom crust develops evenly without burning. Cornmeal has to be stone-ground and medium grind, not the fine stuff in the yellow bag at the grocery store. The texture difference between those 2 products is the difference between something that tastes homemade and something that tastes institutional. I don't add sugar. This separates northern and southern cornbread traditions, but sweetening cornbread makes it a dessert and I want it as a side for chili or greens or just by itself with butter. When it comes out of the oven, the smell fills my apartment for hours. Toasted corn and rendered fat, impossible to replicate with any other cooking method. My roommates always know when I'm making it because the smoke alarm goes off during the preheat. Honestly, that's part of the ritual at this point. The reason I keep making this recipe is that it connects me to a person and a place I can't visit anymore. Getting the ratios closer each time feels like a conversation I'm still having. Best batch so far used a 2:1 cornmeal to flour ratio with just enough buttermilk to bring it together. I wrote that down on a note card I keep inside the skillet when it hangs on the wall.