Set a rack in the lower-middle of the oven, place a 10-inch cast-iron skillet on the rack, and heat the oven to 425°F. Let the empty skillet preheat for at least 15 minutes while you mix the batter. The pan needs to be very hot, not just warm.
Whisk the cornmeal, flour, baking powder, salt, and baking soda together in a large bowl until you can no longer see streaks of soda. This matters — undissolved baking soda will leave yellowish specks in the finished bread.
In a four-cup measure or a medium bowl, whisk the buttermilk, eggs, melted butter, and honey together until the mixture looks uniform and pale gold, about 20 seconds.
Pour the wet ingredients into the dry ingredients. With a rubber spatula, fold from the bottom up just until you no longer see streaks of flour — about a dozen strokes. The batter should still look lumpy. Scatter ¾ cup of the cheddar and the diced jalapeño over the top and fold in with three or four more strokes. Stop. Resist the urge to make it smooth.
Pull the hot skillet from the oven (use a heavy mitt; the handle stays hot for a long time after baking, too). Drop in the remaining 2 teaspoons of butter or bacon drippings and swirl to coat the bottom and sides. The fat should shimmer and just begin to smoke. Scrape the batter into the skillet — you should hear it sizzle on contact — and quickly smooth the top.
Scatter the reserved ¼ cup cheddar across the surface and arrange the jalapeño rings around the edge, one for each future wedge.
Bake until the top is deeply golden, the cheese is bubbling and freckled with brown, and the edges have pulled away from the sides of the pan, 22 to 26 minutes. A wooden skewer inserted into the center should come out clean, with no wet batter clinging to it. If you have an instant-read thermometer, the center will register about 205°F.
Let the cornbread rest in the skillet for 10 minutes — this gives the starches time to set, and a too-warm wedge will crumble. Run a thin knife around the edge, slide the cornbread onto a board, and cut into 8 wedges. Serve warm.