Mix the yeast, water and 1 tbsp flour in a bowl. Let stand about 15 minutes, until mixture is foamy (if the mixture hasn't foamed, start over with new yeast).
In a separate mixing bowl, combine the 2 1/4 cups flour, salt, and brown sugar. Mix well with a whisk.
Place the butter, brie cheese and half of the flour mixture in a food processor. Pulse about ten times, until cheese and butter have been well incorporated into the flour
Pour the contents of the food processor back into the bowl with the remaining flour. Add the buttermilk and water/yeast mixture. Mix well until the contents start to form a dough. Flour a work surface and turn dough out.
Knead until the dough becomes somewhat smooth and elastic (about 6 minutes).
Place dough in an oiled bowl, cover with oiled plastic wrap, and let rise until doubled (about two hours).
Preheat oven to 350 F. Line a baking sheet with parchment paper. Beat the egg with some water in a small bowl to form an egg wash.
Punch down dough. Form dough into small, 1 ½ inch diameter balls, and place on baking sheet. Let rise for about 20 minutes. Brush rolls with egg wash.
Bake for 25-35 minutes, until rolls are golden brown. Honey butter is certainly not a bad idea. Serve warm.