Preheat the oven to 425 degrees . Roll out the puff pastry into a 12-inch square. Set aside four 2-cup bowls; invert 1 bowl onto the pastry and cut out 4 rounds. Place on a parchment-paper-lined baking sheet and brush with the egg. Sprinkle with half of the parmigiano-reggiano cheese. Bake until golden, 12 minutes. Let cool.
In a large saucepan, add the potatoes and enough water to cover. Bring to a boil, salt the water and cook until tender, 7 minutes. Add the kale and cook for 2 minutes; drain.
In a large skillet, heat 2 tablespoons EVOO and the butter over medium-high heat. Add the mushrooms and cook, stirring occasionally, until tender, about 12 minutes. Add the garlic and sage; season with salt and pepper. Cook until the garlic is slightly softened, about 3 minutes. Add the wine and cook until slightly reduced, about 1 minute. Add the cream and cook, stirring, for 1 minute. Remove from the heat and fold in the brie and remaining parmigiano-reggiano until melted. Stir in the potatoes and greens. Fill the bowls with the mushroom mixture and top with the crust.