Wash the portabella mushrooms, then gently remove any portion of the stem remaining in the cap.

Gently press a thick slice of Farmer's Cheese into the bottom part of the mushroom cap.

In a medium, shallow bowl stir together the panko, flour, onion powder, Italian seasoning, salt, and cayenne pepper. In a second bowl, whisk an egg until well beaten.

Dip the portabella (with that fabulous stuffed cheese) into the egg mixture, then into the panko breadcrumb mixture then back into the egg mixture, and back once again into the breadcrumb mixture.

Heat a grill pan to medium/medium-high heat. Drizzle olive oil over the sliced zucchini and onions. Salt and pepper a bit to taste. Place the zucchini and onions into the heated grill pan. Cook until golden lines appear, flip and cook on the opposite side.

Drizzle a bit of olive oil over the top (the rounded, non-cheese) side of the mushroom. Place the portabella top-side-down into the heated grill pan. Cook for 5-6 minutes, until the mushroom cap begins to soften.

Drizzle a bit more olive oil over the bottom (which will now be up on the grill pan). Flip the portabella over (now the cheese side will be down in the pan). Cook just until golden brown then remove from the pan.

Assemble burgers with portabella, sliced tomato, a stack of grilled zucchini and onions, and a heap of basil mayonnaise. Enjoy immediately.

Pairs beautifully with a side of sweet potato fries.