Recipe from Everyday Food magazine:
-place portobello stem-side down on a rimmed baking sheet, brush with a mixture of olive oil & lemon juice, and season with salt & pepper. Put in a 400 degree oven for 15 minutes.
-while the portobello is baking, heat 1 TBSP olive oil in a pot and add a minced garlic clove. Before it starts to brown, add a can of cannellini beans (rinsed), 1/4 cup water, 1 tsp thyme leaves, salt & pepper. Simmer until liquid is almost gone.
-when the portobello comes out of the oven, drain any juices from the pan, flip it over and top with white beans. For the topping, mix breadcrumbs (I used panko) with just enough olive oil to bind them together a little. Mix in some more thyme leaves and crumbled feta. Bake for another 5 minutes, or until the breadcrumbs are browned.