Stuffed Summer Squash Boats with Beef, Shiitake Mushrooms & Swiss Cheese

Preheat the oven to 400 degrees F (204 degrees C). Line a baking sheet with foil or parchment paper.
Slice the squash length-wise. Use a melon baller or small spoon to partially hollow out the seedy center of each squash half (this is where the filling will go).
Arrange the squash on the lined baking sheet, cut side up. Sprinkle lightly with sea salt. Bake 15-20 minutes, until almost fully softened.
Meanwhile, heat olive oil in a skillet over medium heat. Add onions and saute about 7-10 minutes, stirring occasionally, until translucent and slightly browned. Add shiitake mushrooms and garlic. Saute 5-7 minutes, stirring occasionally, until the mushrooms are slightly browned and reduced in size.
Turn the heat up to medium high. Add the ground beef to the skillet. Season with sea salt and black pepper. Saute 7-8 minutes, breaking up the pieces with a spatula or spoon, until the beef is browned and the onions are caramelized.
Remove from heat. Stir in sour cream and half of the shredded Swiss cheese. Spoon the filling into the squash halves.
Bake for 10 minutes, until the squash is cooked through and the filling is bubbly.
Turn the oven to broil. Sprinkle the remaining shredded Swiss cheese evenly on top of the squash boats. Broil 3 minutes, until the cheese is melted and browned.

Ingredients