Dice tomatoes and mince garlic, stir together. Chop onions in a smaller dice than the tomatoes and add to the bowl.
2. Slice baguette into thin slices, about 1/4 of an inch thick. Place in a single layer on a baking sheet lined with foil. Drizzle olive oil lightly over each. Bake in the oven at 350 degrees for 4 minutes. You want the bread crisp on the edges, but still a little soft.
3. Add remaining ingredients to the salsa mixture, except the cheese. Stir until well combined. Salt to taste - add more cayenne for a spicier salsa.
4. When baguette slices are done, remove from oven, top each with a little less than 1/2 Tbsp of Monterey Jack, and return to the oven for 2 minutes, or until cheese is melted.
5. Top each baguette with the salsa mixture. Try not to eat the whole batch by yourself.