1. In a large bowl, stir together the brown sugar and butter until smooth and creamy; then add eggs and vanilla, and beat well. Gradually stir in flour. Set bowl over a hot water bath, and stir to blend ingredients. Cover, and refrigerate overnight.
2. Preheat the galette iron.
3. Shape dough into 1 inch balls, and place in the galette iron. Close the iron, and cook the cookies. This should take about 30 seconds in an electric galette iron, or 2 to 4 minutes in a handheld iron over a medium flame. Carefully remove cookies and cool on wire racks.