Preheat oven to 400 degrees and line a baking sheet with parchment paper (optional, but keeps the mess away). Cut each acorn squash in half, top to bottom OR across the middle. Use the first 2 teaspoons of olive oil to brush each squash, then sprinkle with salt. Place squash halves in oven for 40 minutes, or until fork tender, but still retaining their shape. While the squash is roasting, brown sausage in a skillet until cooked through. Next, add in remaining olive oil, onion and garlic to the pan and cook until veggies are soft. Mix in spinach and sprinkle mixture with a little salt. Cook until spinach wilts. Once squash is finished cooking, use a fork to gently mash the inside. Then divide sausage and veggie mixture evenly among the squash halves. Top each with 2 T of feta cheese and a 1/2 T of pecorino romano. Place squash back in the oven for a few minutes to melt and brown the cheese. Enjoy!