1. Preheat oven to 400°.
2. Coat 2-quart glass or ceramic baking dish with 1 teaspoon oil. Set aside.
3. Bring a large saucepan of water to a boil; add salt and pasta. Cook for 6 minutes or until just barely tender. Drain pasta in a colander over a bowl; reserve 1 cup cooking liquid.
4. Cook bacon in a large skillet over medium heat until crisp. Remove bacon from pan, reserving 2 tablespoons drippings in pan; crumble bacon. Add mushrooms to drippings in pan; cook for 8 minutes or until browned, stirring occasionally. Add pepper, garlic, and spinach (in batches); cook 3 minutes or until spinach wilts, tossing occasionally.
5. Combine yogurt and cheese in a large bowl, stirring until almost smooth. Add pasta and mushroom mixture; toss to combine. Stir in 1/2 cup reserved cooking liquid (or more if mixture looks dry). Spoon pasta mixture into prepared dish. Combine crumbled bacon, panko, and parsley. Drizzle with remaining 3 teaspoons oil; toss to combine. Sprinkle evenly over top of pasta. Bake at 400° for 20 minutes or until golden and bubbly.