Prepare the shirataki noodles according to package directions, ensuring they are well-rinsed and patted very dry.
Cut them into short, bite-sized lengths.
In a small nonstick frying pan, melt the butter and olive oil together over medium-low heat.
Add the sliced mushrooms and sauté until tender and golden, about 3-4 minutes.
Stir in the cooked, diced chicken breast and sauté for one more minute to heat through.
Turn the heat down to low.
Add the heavy cream, prepared shirataki noodles, grated Parmesan, salt, pepper, and garlic powder.
Stir gently and constantly until the sauce has combined, thickened, and everything is warmed through.
Do not allow it to boil.
Pour the tetrazzini onto a serving plate immediately, using a spatula to scrape all of the creamy sauce from the pan.