1 large fennel bulb, trimmed, halved, cored, and sliced crosswise 1/8-inch thick, fronds reserved
1 large yellow onion, halved and sliced 1/8-inch thick
3 tablespoons dry white wine
Salt and pepper
1 baguette, cut on the bias into 24 thin slices
How to Make It
Melt butter with 2 Tbsp. olive oil in a large skillet over medium heat. Add fennel and onion and cook, stirring occasionally, until mixture begins to brown, 20 to 25 minutes. Pour in wine, reduce heat to medium-low, cover and cook, stirring occasionally, until golden brown and soft, 8 to 10 minutes longer. Season with salt and pepper.
Preheat oven to 350°F. Brush both sides of baguette slices with remaining 3 Tbsp. olive oil and place on a baking sheet. Bake until edges are golden, 6 to 8 minutes per side.
Spoon 1 generous Tbsp. of topping onto each toasted baguette slice. Garnish with reserved fennel fronds, if desired.