To prepare the polenta, in a medium saucepan, combine the water, cream, salt, parsley and olive oil and bring to a boil. Slowly add the cornmeal, whisking until combined. Cook until thickened, stirring constantly with a wooden spoon. Remove from the heat and stir in the Parmesan cheese. Let cool.

To prepare the filling, in a large saucepan over medium heat, warm the olive oil. Add the mushrooms, onion and garlic and cook, stirring occasionally, until the onion softens. Add the thyme ad turkey and cook, stirring occasionally, for about 2 minutes, Remove from the heat and let cool. Stir in the fontina cheese.

Preheat the oven to 400°F. Line a baking sheet with parchment paper.

In a shallow pie plate, stir together the bread crumbs and Parmesan cheese. 

Fill a small ice cream scoop with polenta and place the polenta ball in your hand. Press a large indent in the middle of the ball and fill with 1 tablespoon of the turkey-mushroom filling. Cover with the polenta, forming a ball, and roll lightly in the bread crumb mixture. Place on the prepared baking sheet. Repeat with the remaining polenta and filling. Drizzle the polenta balls with olive oil.

Bake the polenta balls until hot, about 10 minutes. Serve with an herb aioli for dipping or drizzling.