To make the caramelized leeks, split one leek down the middle and run under water to remove any dirt. Slice the white and light green parts into half circles. Heat a tablespoon of butter and sautee the leek until caramelized. Add a pinch of salt.
Slice the baguette and toast the bread.
Slather on ricotta and divide the ingredients under each type of ricotta above evenly onto 4 pieces of crostini. Top the savory ones with a little extra flake sea salt.