**Prepare the Crostini**:
- Preheat your oven to 200°C (400°F).
- Slice the baguette or ciabatta into 1/2-inch thick slices.
- Arrange the slices on a baking sheet and brush both sides lightly with olive oil. Sprinkle with salt and pepper.
- Bake in the preheated oven for about 8-10 minutes, or until golden and crispy. Flip halfway through for even toasting.
**Make the Bean Spread**:
- In a bowl, combine the drained cannellini beans, olive oil, minced garlic, lemon juice, chopped parsley, and Dijon mustard (if using).
- Use a fork or potato masher to gently smash the beans until you reach your desired consistency. You can leave it a bit chunky for texture or make it smoother according to your preference.
- Season with salt and pepper to taste.
**Assemble the Crostini**:
- Once the crostini are toasted, remove them from the oven and let them cool slightly.
- Top each crostini with a generous spoonful of the smashed cannellini bean mixture.
**Garnish and Serve**:
- Drizzle with a little extra virgin olive oil and sprinkle with fresh herbs and red pepper flakes if desired.
- Serve immediately while the crostini are still warm.