You might be surprised how dramatically four cups of cherry tomatoes reduce down when slow cooked for a good long while. Feel free to up the volume by 50 percent or more, being sure to give them plenty of room (a second baking sheet might be in order). Fresh Mozzarella or burrata can happily sub in for the ricotta if that's your preference. You can keep leftovers in the fridge moistened with a little more olive oil and covered well for a couple of days.
Using a small bowl, whisk together the honey, balsamic, and olive oil until the honey blends into the mix. Pour over the tomatoes and move the pan around to coat them well. Sprinkle the 1/4 teaspoon salt over the tomatoes and top with a generous couple of grinds of black pepper.
Roast until the juices flow, the tomatoes shrivel and begin to caramelize around the edges, 1 1/4 to 1 1/2 hours. Remove from oven.
To assemble the crostini, spread a teaspoon or 2 of ricotta cheese over a baguette slice, top with a spoonful of roasted tomatoes, add a pinch of fleur de sel or regular salt, finish with a small pinch of chopped basil.