2 tablespoons butter
2 medium or 3 small fennel bulbs, quarter bulb lengthwise and cut crosswise into ¼-inch thick slices
1 leek, trimmed and sliced
Salt & pepper
1 pound potatoes, scrubbed clean and cut crosswise in ¼-inch slices
5 sage leaves, chopped
¼ teaspoon cayenne pepper
¾ cup vegetable broth
½ of a lemon
Grated parmesan