Chicken and Brie Sandwiches with Roasted Cherry Tomatoes

Ingredients (14)

• + 1 pound skinless, boneless chicken breasts add to pantry
• + ½ cup Italian-style salad dressing, or to taste add to pantry
• + 3 ounces Brie cheese, sliced add to pantry
• + 1 tablespoon olive oil, divided add to pantry
• + 2 cups cherry tomatoes, halved add to pantry
• ✓ ¼ teaspoon kosher salt, divided
• + 3 tablespoons balsamic vinegar, divided add to pantry
• + 1 tablespoon chopped fresh basil add to pantry
• + 2 cups fresh spinach leaves add to pantry
• ✓ ¼ cup mayonnaise
• + 1 tablespoon Dijon mustard add to pantry
• + 2 cloves garlic, minced add to pantry
• ✓ ⅛ teaspoon ground black pepper
• + 1 loaf French bread, halved lengthwise add to pantry