Typically it’s meat you’ll be braising, but we stretched the parameters here for a lovely combination of two favorite bulb vegetables. When cooked slowly in a bit of wine and chicken stock, they take on silken textures and rich flavors. The fennel hangs on to a bit of its licorice-like tone, while most of the leeks’ oniony taste converts to a slight sweetness. Two preparation tips: First, like other vegetables, leeks come from the earth, but they don’t like to let go of their beds, so be sure to wash them well; one small grain of dirt will feel like a boulder in your mouth. Second, when trimming leeks, discard roots and all but 2 inches of the green parts; leeks should be 6-8 inches trimmed.
Heat oven to 400º. In a medium-size casserole, arrange leeks in one layer with sliced fennel on top. Pour in stock and wine. Scatter pats of butter over the top and season with salt and pepper. Seal with foil and cook in oven 40 minutes. Then remove foil, and return to oven for 10 minutes more.
In a small bowl, combine Parmesan and breadcrumbs. Scatter over the top of the leeks and bake 5-8 minutes, or until well-browned.