Using a vegetable peeler, create ribbons from the zucchini and set them aside.
Dice the onion and mince the garlic. Clean and slice the mushrooms.
Heat the olive oil in a large skillet over medium heat. Sauté the diced onion until softened, then add the minced garlic and sliced mushrooms, cooking until the mushrooms release their moisture and begin to brown.
Add the light cream and fresh thyme sprigs to the skillet. Stir to combine and let the sauce simmer gently for a couple of minutes. Season with salt and pepper to taste.
Meanwhile, cut the tempeh into thin slices or small cubes. In a separate non-stick pan, lightly sear the tempeh over medium heat until golden on both sides, then stir it into the mushroom ragu.
In a small pot, poach the egg. Additionally, lightly scramble or poach the egg whites in a small pan until just set.
Plate a bed of zucchini ribbons, spoon the warm creamy mushroom ragu over them, then top with the poached egg and egg whites.
Garnish with extra thyme if desired, and serve immediately.