Preheat your oven to 300 degrees.
Trim off some of the fat cap from the brisket. If necessary, cut into smaller portions that will fit your vessel & cooking time. The larger the pieces the better.
Season the brisket liberally with salt & pepper. Get an oiled frying pan quite hot and sear the brisket pieces on all sides to develop a brown crust.
Combine the braising liquid ingredients in a separate, oven-safe pot. Add the brisket & bring the liquid up to a boil.
Cover the pot and move the pot to the oven to braise until tender (approx. 4 hours – until a paring knife goes into the meat without resistance).
Remove the brisket from the braising liquid (reserve the liquid). Cut it into ¼” thick slices.
Optional: Use a food processor to break the panko breadcrumbs down into a finer consistency.
Beat together the two eggs in a small bowl. Put some of the all purpose flour in another bowl. Put panko bread crumbs in yet another bowl, mixed with the porcini powder.
Dip each brisket slice in the flour (just to lightly coat), then the eggs, then the panko bread crumbs, then the eggs again, and finally in the panko one more time.
Saute the cremini mushrooms in oil.
Once the mushrooms have started to soften, add the unsalted butter to the pan.
Move the mushroom slices to the side and put the fluted button mushrooms in the pan, stem-side up.
Continue to cook, flipping the button mushrooms once the tops are browned.
Optional: If your decorative button mushrooms haven’t cooked through at this point (before adding the marsala), move them to the oven to roast until cooked the way you like them.
When the mushrooms have cooked down, deglaze the pan with the marsala wine and add the garlic. Continue to cook until most of the marsala has evaporated.
Pan fry the breaded brisket slices in oil until they’re golden brown on both sides.
Strain the braising liquid & simmer it in a sauce pan until it starts to thicken, then stir in the 3 tbsp of butter.
Serve the brisket slices atop the sliced mushrooms, with the fluted mushrooms as a garnish. Drizzle the plate with the braising liquid sauce.