Preheat your oven to 425°F (220°C). Take your 10-inch cast iron skillet and add the 8 tablespoons of unsalted butter. Place the skillet on the middle rack of the oven.

Allow the butter to melt completely, then continue heating until it begins to brown, which should take about 15 minutes.

Measure out the flour, cornmeal, baking powder, baking soda, sugar, and salt into a large mixing bowl. Stir well to combine and make a well in the center.

Core and finely chop one small jalapeño. Slice the top of the second jalapeño into 6 rounds, about 1/4 inch thick.

If you prefer more heat, finely dice the remaining part of the second jalapeño; if not, set it aside for another purpose.

In a separate bowl, crack the two eggs. Add the sour cream and buttermilk, whisking together until smooth and creamy.

Once browned, remove the hot skillet from the oven. Pour most of the brown butter into a heatproof measuring cup, leaving about 1 tablespoon in the skillet.

Slowly whisk the hot butter into the egg mixture to combine. Pour the wet ingredients into the well in the dry ingredients, stirring gently until just moistened.

Carefully fold in the shredded cheddar cheese and the finely diced jalapeños, ensuring not to over-mix.

Ensure the skillet is well-coated with butter, and pour the cornbread batter into it. Smooth out the surface if necessary and place the 6 jalapeño slices on top for decoration.

Bake the cornbread in the preheated oven for 15 minutes. After this time, insert a wooden skewer into the center; if it comes out clean, the cornbread is ready. If there are a few sticky crumbs, bake for another 5 minutes.