Preheat oven to 375°. Cut off a thin slice from the top of a garlic bulb to expose ends of individual cloves. Remove any loose, papery outer layers. Place garlic bulb, cut side up, on a sheet of foil. Drizzle with 1½ tsp. olive oil. Wrap in foil. Place in a small baking pan. Bake for 35 to 40 minutes or until garlic is brown and soft; set aside.

Meanwhile, place artichokes, olives, sun-dried tomatoes, 1 Tbsp. vinegar and ¼ tsp. salt in a food processor. Cover and pulse until coarsely chopped.

Heat 1 Tbsp. olive oil in medium nonstick skillet over medium heat. Add mushrooms and shallot; cook for 5 to 6 minutes or until mushrooms are golden brown. Add 1 Tbsp. vinegar; cook for 30 to 60 seconds or until vinegar evaporates, stirring frequently. Season to taste with salt.

Place oven rack 6 in. from heat; preheat broiler to HIGH. Line a large rimmed baking pan with foil; set aside. Cut ciabatta horizontally in half. Remove soft bread from the inside of ciabatta halves; reserve bread for another use. Place ciabatta halves, cut sides up, in prepared baking pan. Drizzle each half with 1 Tbsp. olive oil.

Remove garlic from foil; carefully squeeze the base of each garlic clove and push it up and out of its paper husks into a small bowl; mash with a fork until a paste forms. Spread garlic paste in each bread half. Broil for 2 to 3 minutes or until bread is golden and crisp.

To assemble, spread olive mixture in the bottom bread half; spread with burrata. Top with mushrooms; drizzle with remaining 1 Tbsp. vinegar and 1½ tsp. olive oil. Sprinkle with Italian seasoning; top with arugula.

Spread aioli in top bread half. Press top and bottom halves of loaf together to form a sandwich. Cut into serving pieces to serve.