Here's a favorite quick dish that I love to make. Baby portabella mushrooms that have been sautéed in an equal mix of olive oil and butter with minced garlic, onion and thyme.
Start the onions over medium heat, then add the minced garlic and thyme. As the mixture softens, add a splash of balsamic vinegar and let that cook off, then add 8 ounces of sliced 'shrooms. As the mushrooms soften, add an ounce or so of Port wine or any other red wine you happen to have open. I keep a bottle of Port in the fridge for these occasions.
When the mushrooms have cooked down and the liquid has evaporated, take them off heat. The dish above has the mushrooms resting on two slices of ciabatta but another alternative is an open piece of baguette, or use the mushrooms as a side dish.
Top the bread slices with a heaping helping of the mushrooms, cover with thinly sliced cheese of your choosing. Mozzarella is nice...Gruyere is grand and in a pinch, as pictured, Monterrey / Jack does just fine. Slide the slices into a 350° oven for 6 to 8 minutes.