Slice the bread lengthwise. Place both halves, inside up, on a baking sheet.
Preheat oven to 400 degrees F.
Melt ½ cup of butter in a microwave safe cup.
Brush the bread with melted butter.
Toast the bread in the oven for 10 minutes.
In the meantime, melt 2 tablespoons of butter in a large skillet. Add sliced meat and cook until done.
Transfer the meat onto a plate.
Add pepper and onion slices into the pan. Cook until they start to brown, about 2 minutes. Stir often.
Add the water and cook the veggies until most of the water evaporates and the veggies are soft. Scrape the bottom of the pan often.
In a medium saucepan, melt butter over a medium heat.
In a large measuring cup, mix together milk and cornstarch.
Add to the melted butter and cook, whisking constantly, until thicken.
Add both cheeses and cook, stirring constantly, until the cheese is completely melted.
Remove from the heat. It will be thick.
Top the toasted bread with meat, peppers and onions and then the cheese sauce.
Return to the oven and bake for 5 to 7 minutes, or until the cheese sauce starts to bubble.
You can place the bread under a broiler on low setting, for 2 to 3 minutes, watching it the whole time.
Let the bread sit on a cutting board for 10 minutes. Slice and serve.
