Baked Orecchiette with Bacon Breadcrumbs

Name: Baked Orecchiette with Bacon Breadcrumbs
Ingredients: 4 tbsp. salted butter, plus more for the baking dish; 1 1/2 tsp. kosher salt, plus more to taste; 1 lb. orecchiette pasta; 1 large onion, thinly sliced; 4 garlic cloves, minced; 10 oz. frozen chopped spinach, thawed and drained; 1 tsp. black pepper; 2 oz. cream cheese; 3 tbsp. all-purpose flour; 3 c. whole milk; 2 c. monterey jack cheese, grated; 4 slices bacon, chopped; 2 tbsp. salted butter; 1 1/2 c. panko; 1/2 tsp. kosher salt; 1 c. grated parmesan cheese