This is a super simple hors d'oeuvre that is so delicious. Make a few without ham for your vegetarians which you can top with walnuts, pears and a drizzle of honey. In sandwich form this is the epitome of a French sandwich. There is nothing better than eating one of these in a park and thinking of Paris. My cousin Lucy, the younger one (Italian families use the same name for children because children are often named after grandparents or parents), and I enjoyed this heavenly sandwich in Tuileries Gardens when she visited me in Paris when I was a student.
Lightly spread one side of the Baguette Rounds with Dijon Mustard.
Top with 1 slice of Ham and 1 slice of Brie.
Put these under the broiler or in a hot oven for 1-2 minutes just until the cheese melts and gets bubbly. Garnish with some chopped green onion and a black olive.