Heat a grill or broiler to high.
Brush both sides of bread lightly with olive oil, and sprinkle with a pinch of salt
Grill bread lightly on both sides, or heat under the broiler just until bread starts to warm and bubble. Do not let it get to brown.
Remove bread from heat, and spread pesto on one side.
Top pesto with sliced tomatoes, and add cheese if desired.
Turn grill or broiler to low, return pizza to heat just long enough to heat ingredients through and let cheese melt. About 2-3 minutes.