Preheat oven to 375 degrees F. Line a very large cookie sheet with parchment paper or foil; set aside. In a bowl, combine flour, cornmeal, sugar, salt, baking powder, baking soda, dry mustard, black pepper, and cayenne pepper. Stir in cheese and seeds.
In another bowl, combine eggs, buttermilk, and melted butter. Add egg mixture to flour mixture; stir to form a crumbly dough.
Turn dough out onto a lightly floured surface. Gently knead until dough clings together. Divide dough into thirds. Shape into three 10-inch-long loaves. Place loaves on the prepared cookie sheet; flatten slightly.
Bake about 20 minutes or until a toothpick inserted near the centers comes out clean. Cool on cookie sheet for 1 hour.
Preheat oven to 325 degrees F. Using a serrated knife, cut loaves into 1/4-inch slices. Place slices on an ungreased cookie sheet. Bake for 10 minutes. Turn slices over; bake for 10 to 12 minutes more or until crisp and dry (do not overbake). Transfer slices to wire racks and let cool.