Heat a grill pan or outdoor grill to high heat.
Peel up the taters and cut them into small chunks. Place potatoes in a pot and cover with cold water. Cover the pot and bring up to a boil over high heat. Uncover, add salt to season up the potatoes and cook until tender, about 15 minutes.
In a small pot over medium low heat and add vegetable oil, about 1 tablespoon – just eyeball it. Add 2 tablespoons butter in small pieces. When butter melts into oil, add 4 cloves of chopped garlic. Saute garlic 1 to 2 minutes, then add scallions and remove pan from heat and reserve.
Heat a medium nonstick skillet over medium-high heat.
In a large bowl, combine balsamic vinegar, Worcestershire, crushed red pepper flakes, rosemary then whisk in about 1/2 cup extra-virgin olive oil, eyeball it. Turn portobello caps in marinade and transfer to a plate to reserve. Add chicken thighs to remaining marinade and coat evenly. Season 1 side of the chicken thighs, as well as the reserved mushroom caps with salt and pepper then transfer just the thighs to hot grill, seasoned side down. Season the opposite side of the chicken thighs and grill for 6 minutes on each side then transfer to a plate to rest. Add raw marinated mushroom caps to grill and top with a heavy skillet to press down on them as they grill. Cook 3 to 4 minutes on each side until, dark, tender and well-marked.
While chicken thighs and mushrooms cook, add a tablespoon extra-virgin olive oil, a turn of the pan, to hot skillet. Add remaining 2 cloves of garlic, peppers and onions to the skillet season with salt and pepper and cook, tossing frequently, 7 to 8 minutes. Add tomatoes and parsley to the pan and toss to heat through, about 1 minute then remove from heat.
Thinly slice rested chicken thigh meat and grilled mushrooms.
Drain potatoes then return them to the hot pot to evaporate some of the water content. Add the reserved garlic and scallion mixture to the potatoes along with the ricotta, 1/2 cup milk and grated cheese and smash away to combine potatoes with cheeses and milk. Season the super-mashers with salt and pepper.
Pile up 1/4 of the potatoes on each plate. Top each pile with 1/4 of chicken, mushrooms and sauce and serve immediately. Yum-o!