Add pasta to boiling water and cook, stirring occasionally, until al dente, 8-10 minutes. Drain pasta. Reserve pot; no need to wipe clean. While pasta cooks, make sauce.

Mince garlic. Place a small pot over medium heat and add 2 tsp. olive oil and half the garlic (reserve remaining for garlic bread) to hot pot. Cook until fragrant, 1-2 minute. Add white wine and cook 1 minute. Stir in crushed tomatoes, 1/2 cup water, and oregano. Bring to a boil, reduce to a simmer, and cook, stirring often, 8-10 minutes. Season to taste with salt and pepper. While sauce simmers, prepare ingredients.

Cut mushrooms into 1/4" slices. Halve baguette lengthwise and slice each half on an angle, creating four wedges.

Return pot used to cook pasta to medium-high heat. Add 1 Tbsp. olive oil and mushrooms to hot pot and cook until lightly browned, 2-3 minutes. Stir in spinach and cook until wilted, 1 minute. Remove from burner and add sauce and cooked pasta. Toss to combine.

Add half the pasta to prepared casserole dish and top with half the mozzarella. Add remaining pasta, and sprinkle with pecorino and remaining mozzarella. Bake until top is golden brown, 18-20 minutes. While pasta bakes, spread butter and remaining garlic on baguette slices. Halfway through pasta cooking time, place baguette on prepared baking sheet and bake until golden brown, 7-9 minutes.

Serve pasta straight from casserole dish along with garlic bread.