Preheat the oven to 400 degrees F.
Remove the stems from the mushrooms and set them aside in a medium bowl.
In a large mixing bowl, prepare the filling by mixing together the drained salmon, Neufchatel cream cheese, Greek yogurt, lemon juice, parmesan cheese, cheddar cheese, green onions, breadcrumbs, garlic powder, salt, and pepper.
Take the destemmed mushrooms and toss them with olive oil to lightly coat. Fill each mushroom with the salmon filling mixture, then place on the baking sheet.
Bake at 400 degrees F for 15 to 20 minutes, or until mushrooms are cooked through and tender, and filling is hot. Let cool for a few minutes, then enjoy!