The bread should be about 22 inches long and cut in 1/2 lengthwise.
Preheat the oven to 400 degrees.
In a large bowl, cream together the butter and olive oil.
Combine into the above, using a rubber spatula, the onions, parsley, garlic, Essence, lemon juice, pepper sauce, and salt.
Spread a large sheet of heavy aluminum foil on a work surface; place the 2 bread halves in the middle.
Spread the mixture evenly over both halves of the bread.
Cover the bottom 1/2 evenly with the cheese and top with the other loaf 1/2.
Wrap them together in the foil; place this on a baking sheet.
Bake until the crust is hard and the filling is gooey, about 20 minutes.
Remove from the oven; unwrap; cut into 2-inch thick slices.