Preheat the broiler.

In a small saucepan over medium heat, combine the water, sugar, lemon zest, and vanilla bean halves. Bring to a boil and cook for 10 minutes. Add the apricots, lower the heat, and cook for 5 additional minutes. Turn off the heat and let the apricots cool in the syrup for several minutes.

Butter the bread slices and place under the broiler until toasted. Remove the slices and generously spread them with the ricotta cheese. Top with cooked apricot halves, drizzle with the apricot syrup, and sprinkle with sugar. Heat for a few minutes under the broiler.