Wash and dry all produce. Preheat oven to 400 degrees. Halve and core pear; slice into 1/2-inch wedges. Cut one baguette into 1/2-inch cubes. Place pear and baguette cubes on separate sides of a foil-lined baking sheet. Toss each with salt, pepper, and a drizzle of oil. Bake until baguette is crispy and pears have softened a bit, about 10 minutes.

Trim, then thinly slice mushrooms. Heat a drizzle of oil in a large pan over medium-high heat. Add mushrooms and cook until tender, about 7 minutes. Remove from pan and set aside. Once pear and baguette cubes have baked 10 minutes, remove cubes from sheet and set aside. Flip pear and continue baking until browned, another 10 minutes.

Heat a drizzle of oil in pan used for mushrooms over medium-high heat. Season steak all over with salt and pepper. Add to pan and cook to desired doneness, 3-5 minutes per side. Remove from pan and let rest at least 5 minutes before thinly slicing against the grain.

While steak cooks, halve remaining baguette lengthwise, then cut in half again crosswise to create quarters. Place half the garlic herb butter and 1 TBSP olive oil in a small bowl. Heat in microwave until butter is melted, about 30 seconds. Drizzle mixture over cut sides of baguette. Place on another baking sheet and toast in oven until golden, 6-7 minutes.

Add 1/3 cup water, 1 tsp balsamic vinegar (we'll use the rest in the next step), demi-glace, and mushrooms to same pan over medium-high heat and stir, scraping up any brown bits on bottom of pan. Bring to a simmer, then reduce heat to low and let thicken, about 1 minute. Add remaining garlic herb butter and stir until melted.

Toss together arugula, baguette cubes, remaining balsamic vinegar, and 11/2 TBSP olive oil in a medium bowl. Season with salt and pepper. Divide steak, salad, and garlic bread between plates. Drizzle sauce over steak. Top salad with pear and crumble over ricotta salata.