Heat your oven to 425 degrees. Break the mushrooms down into four equal pieces and lay out on a bare sheet tray light sprayed with non stick spray.
Roast the in the oven for about 15 minutes until the mushrooms are slightly withered and they begin to caramelize. Turn them throughout their time in the oven, so that they cook evenly.
While they are roasting, heat a heavy bottomed pot or cast iron skillet over medium heat.
Once the mushrooms have cooked enough, remove them from the oven and place them in the hot pan, first dry, then after a minute or two add enough vegetable oil to coat the mushrooms.
Sauté the mushrooms until they caramelize deeply and pick up color. Add the miso honey mixture to the pan and toss the mushrooms around in the sauce until it reduces and fully coats the caramelized mushrooms.
To plate mound some of the mash on the plate a top with the roasted mushrooms. Finish with a little thinly sliced scallion greens.