A great way to serve portabellas is to stuff them. Truth be told, the cap of a portabella, though large, is not very deep. What you really end up with is something more akin to a portabella pizza.
Prep the caps:
Stem the mushrooms and scrape the gills out of the caps with a teaspoon. Rub the caps generously with olive oil on both sides, season with salt and pepper, and either sauté, grill or broil them until tender, about 5 minutes per side.
Make the stuffing and broil:
Heat 1-1/2 Tbs. olive oil in a medium skillet over medium-high heat. Add the rosemary and heat for a few minutes to release its aroma. Add the garlic and cook until fragrant. Add the beans and cook another 5 minutes. Add the tomatoes, toss to combine, cook for a minute or so, and season with salt and pepper. Discard the rosemary and divide the filling among the prepared portabella caps. Sprinkle each cap with some grated Fontina and broil briefly to melt the cheese.
Photo: Judi Rutz