French Onion Soup Crepes

**Prepare the Crepe Batter:** In a blender or bowl, whisk together flour, eggs, milk, melted butter, and salt until smooth. Let the batter rest for at least 30 minutes at room temperature.

**Caramelize the Onions:** In a large skillet, melt butter over medium-low heat. Add sliced onions and cook, stirring occasionally, until softened and deeply caramelized, about 30-40 minutes. Stir in brown sugar and sherry (if using) during the last 5 minutes of cooking. Season with salt and pepper to taste. Remove from heat and set aside.

**Make the Beef Broth Reduction:** In a saucepan, combine beef broth, thyme sprigs (if using), and bay leaf (if using). Bring to a simmer over medium heat. Reduce the broth until it has thickened slightly and has about 1 cup of liquid remaining, about 20-25 minutes. Strain the broth through a fine-mesh sieve to remove thyme and bay leaf. Keep warm.

**Cook the Crepes:** Heat a lightly oiled crepe pan or non-stick skillet over medium heat. Pour about 1/4 cup of crepe batter onto the hot pan, swirling to coat the bottom evenly. Cook for 1-2 minutes per side, or until lightly golden. Repeat with remaining batter.

**Assemble the Crepes:** Lay a crepe flat on a plate. Spread a generous amount of caramelized onions in the center, then sprinkle with shredded Gruyere cheese. Fold the crepe in half, then in half again to form a triangle. Repeat with remaining crepes.

**Bake the Crepes (optional):** For a more melted cheese, place the filled crepes on a baking sheet and bake in a preheated oven at 350°F (175°C) for 5-7 minutes, or until the cheese is melted and bubbly.

**Serve:** Drizzle each crepe with the beef broth reduction and serve immediately.