Cook the pasta in boiling salted water until just al dente, then drain and set aside.
Heat the olive oil and butter in a skillet over medium heat until melted and fragrant, about 1 minute.
Add the sliced mushrooms to the skillet and sauté, stirring occasionally, until they release their moisture and turn golden brown, approximately 5-7 minutes.
Stir in the minced garlic and cook for another 30 seconds until fragrant, taking care not to burn it.
Add the chopped spinach to the skillet and cook, stirring, until it wilts and reduces in volume, about 2-3 minutes.
Season the mixture with salt and pepper to taste, then remove from heat.
Combine the cooked pasta with the sautéed mushrooms and spinach mixture, mixing well to evenly distribute the ingredients.
Transfer the pasta mixture into a baking dish and sprinkle the shredded cheese evenly over the top.
Place the dish in a preheated oven at 375°F (190°C) and bake uncovered until the cheese is bubbly and golden, about 15-20 minutes.
Remove from oven and let sit for a few minutes; the cheese will set slightly and the aroma will be irresistible.
Scoop the baked mushroom and spinach pasta onto plates and enjoy while hot, enjoying the cheesy, crispy edges and tender vegetables.
