Brush one side of the bread with the olive oil. Place the oil brushed side of the bread down on the work surface.
Spread the side facing up with the mayonnaise. Place the roasted beef in loose layers over the mayonnaise and top with the grated cheddar.
Place the sandwich on a baking pan. Position the oven rack in the lower slot on an electric convection oven with the rack oriented upwards. Set your convection oven to Toast on Medium setting.
Place the sandwich in the oven and toast until the cheese is bubbling and golden.