In a large bowl, whisk cornmeal, 1 1/2 cup flour, sugar, baking powder, baking soda, onion powder, and cayenne.
With the large holes of a box grater, shred butter over top of flour mixture, stopping 2 or 3 times to toss flour over the butter to prevent clumping.
Stir until combined, breaking up any large clumps.
Add buttermilk and stir until just moistened.
Turn dough onto a lightly floured surface and knead briefly with floured hands just until dough forms a ball.
Divide into 2 equal pieces and press each into a thick disk.
Wrap each loosely in plastic wrap or parchment and freeze for 10 minutes. Note: Do not freeze for longer, or dough will be too stiff to roll.
Preheat oven to 400°F/200°C.
Pat the hot dogs dry with paper towel and stick a skewer into each, about 2-3 inches.
On a large plate, add remaining 1/3 cup flour.
In a wide, shallow bowl (I use a pie plate), lightly beat egg whites.
Remove 1 disk of dough from freezer and transfer to a lightly floured surface.
Roll into a 13-in-wide oval, only a scant 1/4 inch thick.
Cut into about 4 strips that will wrap around the hot dogs, about 3 1/4 inches wide depending on the size of the hot dogs.
Dip a hot dog in flour, shaking off excess, then dip in egg whites.
Wrap with dough, gently pushing the seam together to seal.
Pinch off excess dough from ends to completely cover the tip and leave a scant 1/4 inch of hot dog exposed at the skewer end.
Place on a parchment-lined (or use a silicone baking mat) baking sheet (leave 1-2 inches between the corn dogs).
Repeat with remaining dough strips and 3 hot dogs.
Wrap excess dough scraps and return them to freezer.
Repeat the process with remaining disk of dough and 4 hot dogs.
Knead dough scraps just to combine, without over-working the dough.
Roll out and cut into 2 strips.
Wrap the remaining 2 hot dogs.
Bake until bottoms are golden brown and dough is cooked through, 14-16 minutes.
Notes
If you would like to try subbing honey for the sugar, do not add the sugar and instead add 2 1/2 Tbsp honey when you stir in the buttermilk. Then adjust cooking temperature to 375.