Start by preheating your oven to 400°F. Slice the baguette into even pieces so they toast uniformly. Arrange them on a baking sheet and drizzle lightly with olive oil before seasoning with salt and pepper.
Bake the slices for about 6–7 minutes until golden and crisp. Keep an eye on them because baguette slices can brown quickly. The crostini should feel crunchy but not too hard.
Heat olive oil in a skillet over medium heat and add minced garlic with red pepper flakes. Stir for about 30 seconds until fragrant, then add lemon zest and lemon juice for brightness.
Add fresh spinach gradually and cook until wilted down completely. Continue stirring until most of the moisture evaporates so the dip stays creamy instead of watery.
Lower the heat and stir in softened cream cheese and mozzarella cheese. Mix slowly until everything becomes smooth and creamy without lumps.
Add sour cream, Parmesan cheese, olives, and chopped herbs. Stir gently until all ingredients are evenly combined and coated in the creamy mixture.
Spread a generous spoonful of the spinach olive mixture onto each toasted baguette slice. Make sure every piece gets enough topping for maximum flavor.
Place the assembled crostini back onto the baking tray. Broil them for 3–4 minutes until the tops become bubbly and lightly golden.
Remove the crostini from the oven carefully and top with extra olives, herbs, and cracked black pepper. The fresh toppings add color and extra flavor.
Serve immediately while warm and crispy. The creamy topping paired with crunchy bread creates the perfect appetizer texture.