Step 1

Cut a lengthwise slit from stem to bottom of each chile. Make a crosswise incision at stem end, forming a T.

Step 2

Pry open each chile as if it was a book to expose the ribs and seeds, then devein and seed using the tip of a paring knife to scrape the inside clean.

Step 3

Stir together cheeses, hot sauce, 1/4 teaspoon pepper, and 3/4 teaspoon salt.

Step 4

Fill/pack the chiles with cheese mixture, pressing seams closed after filling, so that cheese is compacted and chile retains its shape.

Step 5

Stir together bread crumbs, oregano, and 1/4 teaspoon each of salt and pepper in another shallow bowl.

Step 6

Pour the buttermilk into a high sided bowl or drinking glass. Working one at a time, roll the chiles in flour until uniformly covered shaking off any excess. Dip the chiles in the buttermilk, letting excess drip off, then coat with the bread crumbs. Repeat coating with buttermilk and panko to form a second layer. Transfer to a parchment lined baking sheet and repeat with the remaining chiles. Once all of the chiles have been coated, place the baking sheet in the freezer until frozen through.

Step 7

Heat 2 inches oil to 325°F in a medium saucepan. Fry chiles in 3 batches, stirring occasionally, until golden brown all over, 5 to 6 minutes per batch. Transfer to several layers of paper towels to drain. Return oil to 325°F between batches.