In a large bowl, combine the pancake mix with enough water to make a thin batter. Add nutmeg, cinnamon, vanilla, sugar and eggs. Whisk together until smooth, about 3 minutes.

In a medium bowl, mix together walnuts, brown sugar, and banana slices.

Slice the ends off the French bread. Starting at 1 end, measure about a half inch down the loaf and slice the bread 3/4 of the way through. Measure about another half inch, and slice cleanly through the bread. You should have a 1-inch slice of bread with a cut down the middle. Repeat this process until the bread is all sliced up.

Take a piece of the cut French bread and stuff a few tablespoons of the banana mixture into the slit in the middle. Add a good amount, but do not overstuff so that the mixture won't stay in the center. Repeat until all the slices are stuffed.

Preheat a skillet or flat-top grill over medium-high heat. When the pan is hot, coat it with 2 tablespoons of butter.

Pour the crushed-up cornflakes onto a plate. Take a slice of stuffed bread and dip it into the egg mixture, coating both sides liberally. Then press the bread into the cornflakes and flip it to coat both sides. Place the bread on the grill or skillet and cook until golden brown, about 3 minutes per side. Flip the toast over and cook the other side. Repeat the coating and cooking process for each slice of bread, and add more butter to the grill or skillet as necessary, about 2 tablespoons of butter per slice.