Adjust rack to top position (top and middle positions for 4 servings) and preheat oven to 425 degrees. Wash and dry produce. Trim and slice zucchini crosswise into 1/2-inch-thick rounds. Peel and mince or grate garlic. Halve, peel, and finely chop shallot. Halve demi-baguette lengthwise.

Toss zucchini on a baking sheet with Italian Seasoning, a drizzle of oil, salt, and pepper. Roast on top rack for 12 minutes (you’ll add the garlic bread then).

Meanwhile, place 1 TBSP butter (2 TBSP for 4 servings) and garlic in a small microwave-safe bowl. Microwave until softened, 10 seconds. Spread onto cut sides of baguette; season with salt and pepper. Once zucchini has roasted 12 minutes, carefully toss and push to one side of sheet. Place garlic bread cut sides up on empty side. (For 4, leave zucchini roasting; add bread to a second sheet and toast on middle rack.) Roast until zucchini is tender and bread is toasted, 3-5 minutes more.

While garlic bread toasts, pat steak dry with paper towels; season all over with salt and pepper. Heat a drizzle of oil in a large pan over medium-high heat. Add steak and cook to desired doneness, 4-7 minutes per side. Turn off heat; remove from pan and set aside to rest.

Heat a drizzle of oil in pan used for steak over medium heat. Add shallot and cook, stirring, until softened, 1 minute. Stir in stock concentrate and 1/4 cup water (1/3 cup for 4 servings). Bring to a simmer and cook, scraping up any browned bits from bottom of pan, until reduced by half, 2-3 minutes. Turn off heat; stir in 1 TBSP butter. Season with salt and pepper.

Halve garlic bread on a diagonal if desired. Divide steak, zucchini, and garlic bread between plates. Top steak with sauce and serve.